diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4a385ab3..e99c3503 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -132,7 +132,7 @@ jobs:
     steps:
     - name: Checkout the repository
       uses: actions/checkout@master
-    - name: Do Qemu build and test
-      run: |
-        docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
-        docker run --rm -v .:/janet --platform linux/s390x ubuntu bash -c "apt-get -y update && apt-get -y install git build-essential && cd /janet && make -j3 && make test"
+    - name: Enable qemu
+      run: docker run --privileged --rm tonistiigi/binfmt --install s390x
+    - name: Build and run on emulated architecture
+      run: docker run --rm -v .:/janet --platform linux/s390x alpine sh -c "apk update && apk add --no-interactive git build-base && cd /janet && make -j3 && make test"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11eebf84..da897093 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,12 @@
 # Changelog
 All notable changes to this project will be documented in this file.
 
-## ??? - Unreleased
+## Unreleased - ???
+- Make `ffi/write` append to a buffer instead of insert at 0 by default.
+
+## 1.38.0 - 2025-03-18
+- Add `bundle/replace`
+- Add CLI flags for the `bundle/` module to install and manage bundles.
 - Improve `?` peg special termination behavior
 - Add IEEE hex floats to grammar.
 - Add buffer peg literal support
diff --git a/LICENSE b/LICENSE
index 440e8c30..ceaa6a0e 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2023 Calvin Rose and contributors
+Copyright (c) 2025 Calvin Rose and contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of
 this software and associated documentation files (the "Software"), to deal in
diff --git a/Makefile b/Makefile
index 8e411d3b..5e474233 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-# Copyright (c) 2024 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
@@ -57,6 +57,7 @@ LDFLAGS?=-rdynamic
 LIBJANET_LDFLAGS?=$(LD_FLAGS)
 RUN:=$(RUN)
 
+
 COMMON_CFLAGS:=-std=c99 -Wall -Wextra -Isrc/include -Isrc/conf -fvisibility=hidden -fPIC
 BOOT_CFLAGS:=-DJANET_BOOTSTRAP -DJANET_BUILD=$(JANET_BUILD) -O0 $(COMMON_CFLAGS) -g
 BUILD_CFLAGS:=$(CFLAGS) $(COMMON_CFLAGS)
@@ -94,12 +95,18 @@ endif
 endif
 
 # Mingw
+MINGW_COMPILER=
 ifeq ($(findstring MINGW,$(UNAME)), MINGW)
+	MINGW_COMPILER=gcc
 	CLIBS:=-lws2_32 -lpsapi -lwsock32
 	LDFLAGS:=-Wl,--out-implib,$(JANET_IMPORT_LIB)
 	LIBJANET_LDFLAGS:=-Wl,--out-implib,$(JANET_LIBRARY_IMPORT_LIB)
 	JANET_TARGET:=$(JANET_TARGET).exe
 	JANET_BOOT:=$(JANET_BOOT).exe
+	COMPILER_VERSION:=$(shell $(CC) --version)
+	ifeq ($(findstring clang,$(COMPILER_VERSION)), clang)
+		MINGW_COMPILER=clang
+	endif
 endif
 
 
@@ -209,9 +216,14 @@ build/%.bin.o: src/%.c $(JANET_HEADERS) $(JANET_LOCAL_HEADERS) Makefile
 ########################
 
 ifeq ($(UNAME), Darwin)
-SONAME=libjanet.1.37.dylib
+SONAME=libjanet.1.38.dylib
 else
-SONAME=libjanet.so.1.37
+SONAME=libjanet.so.1.38
+endif
+
+ifeq ($(MINGW_COMPILER), clang)
+	SONAME=
+	SONAME_SETTER=
 endif
 
 build/c/shell.c: src/mainclient/shell.c
diff --git a/meson.build b/meson.build
index 137d7809..afd84e7a 100644
--- a/meson.build
+++ b/meson.build
@@ -1,4 +1,4 @@
-# Copyright (c) 2024 Calvin Rose and contributors
+# Copyright (c) 2025 Calvin Rose and contributors
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
@@ -20,7 +20,7 @@
 
 project('janet', 'c',
   default_options : ['c_std=c99', 'build.c_std=c99', 'b_lundef=false', 'default_library=both'],
-  version : '1.37.1')
+  version : '1.38.0')
 
 # Global settings
 janet_path = join_paths(get_option('prefix'), get_option('libdir'), 'janet')
@@ -39,6 +39,15 @@ native_thread_dep = dependency('threads', native : true)
 # Deps
 m_dep = cc.find_library('m', required : false)
 dl_dep = cc.find_library('dl', required : false)
+
+# for MINGW/MSYS2
+native_ws2_dep = native_cc.find_library('ws2_32', required: false)
+native_psapi_dep = native_cc.find_library('psapi', required: false)
+native_wsock_dep = native_cc.find_library('wsock32', required: false)
+ws2_dep = cc.find_library('ws2_32', required: false)
+psapi_dep = cc.find_library('psapi', required: false)
+wsock_dep = cc.find_library('wsock32', required: false)
+
 android_spawn_dep = cc.find_library('android-spawn', required : false)
 thread_dep = dependency('threads')
 
@@ -176,8 +185,8 @@ mainclient_src = [
   'src/mainclient/shell.c'
 ]
 
-janet_dependencies = [m_dep, dl_dep, android_spawn_dep]
-janet_native_dependencies = [native_m_dep, native_dl_dep, native_android_spawn_dep]
+janet_dependencies = [m_dep, dl_dep, android_spawn_dep, ws2_dep, psapi_dep, wsock_dep]
+janet_native_dependencies = [native_m_dep, native_dl_dep, native_android_spawn_dep, native_ws2_dep, native_psapi_dep, native_wsock_dep]
 if not get_option('single_threaded')
   janet_dependencies += thread_dep
   janet_native_dependencies += native_thread_dep
diff --git a/src/boot/array_test.c b/src/boot/array_test.c
index 39022a3e..e1b545cc 100644
--- a/src/boot/array_test.c
+++ b/src/boot/array_test.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/boot/boot.c b/src/boot/boot.c
index 0ccc8ddb..df1b180f 100644
--- a/src/boot/boot.c
+++ b/src/boot/boot.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/boot/boot.janet b/src/boot/boot.janet
index 75f8bf2f..c3e292ec 100644
--- a/src/boot/boot.janet
+++ b/src/boot/boot.janet
@@ -1,5 +1,5 @@
 # The core janet library
-# Copyright 2024 © Calvin Rose
+# Copyright 2025 © Calvin Rose
 
 ###
 ###
@@ -3984,7 +3984,7 @@
 
 (def- safe-forms {'defn true 'varfn true 'defn- true 'defmacro true 'defmacro- true
                   'def is-safe-def 'var is-safe-def 'def- is-safe-def 'var- is-safe-def
-                  'defglobal is-safe-def 'varglobal is-safe-def})
+                  'defglobal is-safe-def 'varglobal is-safe-def 'defdyn true})
 
 (def- importers {'import true 'import* true 'dofile true 'require true})
 (defn- use-2 [evaluator args]
@@ -4118,7 +4118,11 @@
     [manifest]
     (def bn (get manifest :name))
     (def manifest-name (get-manifest-filename bn))
-    (spit manifest-name (string/format "%j\n" manifest)))
+    (def b @"")
+    (buffer/format b "%j" manifest) # make sure it is valid jdn
+    (buffer/clear b)
+    (buffer/format b "%.99m\n" manifest)
+    (spit manifest-name b))
 
   (defn bundle/manifest
     "Get the manifest for a give installed bundle"
@@ -4137,7 +4141,7 @@
       (os/cd workdir)
       ([_] (print "cannot enter source directory " workdir " for bundle " bundle-name)))
     (defer (os/cd dir)
-      (def new-env (make-env (curenv)))
+      (def new-env (make-env))
       (put new-env *module-cache* @{})
       (put new-env *module-loading* @{})
       (put new-env *module-make-env* (fn make-bundle-env [&] (make-env new-env)))
@@ -4152,7 +4156,6 @@
     [module bundle-name hook & args]
     (def hookf (module/value module (symbol hook)))
     (unless hookf (break))
-    (def manifest (bundle/manifest bundle-name))
     (def dir (os/cwd))
     (os/cd (get module :workdir "."))
     (defer (os/cd dir)
@@ -4271,8 +4274,8 @@
     (assertf (not (string/check-set "\\/" bundle-name))
              "bundle name %v cannot contain path separators" bundle-name)
     (assert (next bundle-name) "cannot use empty bundle-name")
-    (assert (not (fexists (get-manifest-filename bundle-name)))
-            "bundle is already installed")
+    (assertf (not (fexists (get-manifest-filename bundle-name)))
+             "bundle %v is already installed" bundle-name)
     # Setup installed paths
     (prime-bundle-paths)
     (os/mkdir (bundle-dir bundle-name))
@@ -4345,14 +4348,15 @@
       (spit install-hook b))
     dest-dir)
 
-  (defn bundle/reinstall
-    "Reinstall an existing bundle from the local source code."
-    [bundle-name &keys new-config]
+  (defn bundle/replace
+    "Reinstall an existing bundle from a new directory. Similar to bundle/reinstall,
+     but installs the replacement bundle from any directory. This is necesarry to replace a package without
+     breaking any dependencies."
+    [bundle-name path &keys new-config]
     (def manifest (bundle/manifest bundle-name))
-    (def path (get manifest :local-source))
     (def config (get manifest :config @{}))
     (def s (sep))
-    (assert (= :directory (os/stat path :mode)) "local source not available")
+    (assertf (= :directory (os/stat path :mode)) "local source %v not available" path)
     (def backup-dir (string (dyn *syspath*) s bundle-name ".backup"))
     (rmrf backup-dir)
     (def backup-bundle-source (bundle/pack bundle-name backup-dir true))
@@ -4365,6 +4369,14 @@
     (rmrf backup-bundle-source)
     bundle-name)
 
+  (defn bundle/reinstall
+    "Reinstall an existing bundle from the local source code."
+    [bundle-name &keys new-config]
+    (def manifest (bundle/manifest bundle-name))
+    (def path (get manifest :local-source))
+    (bundle/replace bundle-name path ;(kvs new-config))
+    bundle-name)
+
   (defn bundle/add-directory
     "Add a directory during the install process relative to `(dyn *syspath*)`"
     [manifest dest &opt chmod-mode]
@@ -4431,10 +4443,11 @@
     `Shorthand for adding scripts during an install. Scripts will be installed to
     (string (dyn *syspath*) "/bin") by default and will be set to be executable.`
     [manifest src &opt dest chmod-mode]
-    (default dest (last (string/split "/" src)))
+    (def s (sep))
+    (default dest (last (string/split s src)))
     (default chmod-mode 8r755)
-    (os/mkdir (string (dyn *syspath*) (sep) "bin"))
-    (bundle/add-file manifest src (string "bin" (sep) dest) chmod-mode))
+    (os/mkdir (string (dyn *syspath*) s "bin"))
+    (bundle/add-file manifest src (string "bin" s dest) chmod-mode))
 
   (defn bundle/update-all
     "Reinstall all bundles"
@@ -4497,6 +4510,12 @@
    "-nocolor" "n"
    "-color" "N"
    "-library" "l"
+   "-install" "b"
+   "-reinstall" "B"
+   "-uninstall" "u"
+   "-update-all" "U"
+   "-list" "L"
+   "-prune" "P"
    "-lint-warn" "w"
    "-lint-error" "x"})
 
@@ -4507,7 +4526,7 @@
 
   (setdyn *args* args)
 
-  (var should-repl false)
+  (var should-repl nil)
   (var no-file true)
   (var quiet false)
   (var raw-stdin false)
@@ -4562,6 +4581,12 @@
                --library (-l) lib      : Use a module before processing more arguments
                --lint-warn (-w) level  : Set the lint warning level - default is "normal"
                --lint-error (-x) level : Set the lint error level - default is "none"
+               --install (-b) dirpath  : Install a bundle from a directory
+               --reinstall (-B) name   : Reinstall a bundle by bundle name
+               --uninstall (-u) name   : Uninstall a bundle by bundle name
+               --update-all (-U)       : Reinstall all installed bundles
+               --prune (-P)            : Uninstalled all bundles that are orphaned
+               --list (-L)             : List all installed bundles
                --                      : Stop handling options
              ```)
            (os/exit 0)
@@ -4606,6 +4631,30 @@
              ((thunk) ;subargs)
              (error (get thunk :error)))
            math/inf)
+     "b"
+     (compif (dyn 'bundle/install)
+       (fn [i &] (bundle/install (in args (+ i 1))) (set no-file false) (if (= nil should-repl) (set should-repl false)) 2)
+       (fn [i &] (eprint "--install not supported with reduced os") 2))
+     "B"
+     (compif (dyn 'bundle/reinstall)
+       (fn [i &] (bundle/reinstall (in args (+ i 1))) (set no-file false) (if (= nil should-repl) (set should-repl false)) 2)
+       (fn [i &] (eprint "--reinstall not supported with reduced os") 2))
+     "u"
+     (compif (dyn 'bundle/uninstall)
+       (fn [i &] (bundle/uninstall (in args (+ i 1))) (set no-file false) (if (= nil should-repl) (set should-repl false)) 2)
+       (fn [i &] (eprint "--uninstall not supported with reduced os") 2))
+     "P"
+     (compif (dyn 'bundle/prune)
+       (fn [i &] (bundle/prune) (set no-file false) (if (= nil should-repl) (set should-repl false)) 1)
+       (fn [i &] (eprint "--prune not supported with reduced os") 1))
+     "U"
+     (compif (dyn 'bundle/update-all)
+       (fn [i &] (bundle/update-all) (set no-file false) (if (= nil should-repl) (set should-repl false)) 1)
+       (fn [i &] (eprint "--update-all not supported with reduced os") 1))
+     "L"
+     (compif (dyn 'bundle/list)
+       (fn [i &] (each l (bundle/list) (print l)) (set no-file false) (if (= nil should-repl) (set should-repl false)) 1)
+       (fn [i &] (eprint "--list not supported with reduced os") 1))
      "d" (fn [&] (set debug-flag true) 1)
      "w" (fn [i &] (set warn-level (get-lint-level i)) 2)
      "x" (fn [i &] (set error-level (get-lint-level i)) 2)
diff --git a/src/boot/buffer_test.c b/src/boot/buffer_test.c
index f53be7b8..0698e3c9 100644
--- a/src/boot/buffer_test.c
+++ b/src/boot/buffer_test.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/boot/number_test.c b/src/boot/number_test.c
index 4c469ba8..15bd085f 100644
--- a/src/boot/number_test.c
+++ b/src/boot/number_test.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/boot/system_test.c b/src/boot/system_test.c
index 9e1ced24..4fcd4c66 100644
--- a/src/boot/system_test.c
+++ b/src/boot/system_test.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/boot/table_test.c b/src/boot/table_test.c
index 121a07e1..1b07a577 100644
--- a/src/boot/table_test.c
+++ b/src/boot/table_test.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/conf/janetconf.h b/src/conf/janetconf.h
index 7fc77bc0..35f1b58d 100644
--- a/src/conf/janetconf.h
+++ b/src/conf/janetconf.h
@@ -4,10 +4,10 @@
 #define JANETCONF_H
 
 #define JANET_VERSION_MAJOR 1
-#define JANET_VERSION_MINOR 37
-#define JANET_VERSION_PATCH 1
+#define JANET_VERSION_MINOR 38
+#define JANET_VERSION_PATCH 0
 #define JANET_VERSION_EXTRA ""
-#define JANET_VERSION "1.37.1"
+#define JANET_VERSION "1.38.0"
 
 /* #define JANET_BUILD "local" */
 
diff --git a/src/core/abstract.c b/src/core/abstract.c
index 3a97e9b8..dab8536d 100644
--- a/src/core/abstract.c
+++ b/src/core/abstract.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/array.c b/src/core/array.c
index e11ae52f..bda15159 100644
--- a/src/core/array.c
+++ b/src/core/array.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/asm.c b/src/core/asm.c
index 7ec4292f..4f54623a 100644
--- a/src/core/asm.c
+++ b/src/core/asm.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/buffer.c b/src/core/buffer.c
index d2e89f8c..06e3f9f9 100644
--- a/src/core/buffer.c
+++ b/src/core/buffer.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/bytecode.c b/src/core/bytecode.c
index 121811e7..7f1acdac 100644
--- a/src/core/bytecode.c
+++ b/src/core/bytecode.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/capi.c b/src/core/capi.c
index af6ea582..5a6a2e68 100644
--- a/src/core/capi.c
+++ b/src/core/capi.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/cfuns.c b/src/core/cfuns.c
index b9c8a95b..960bd502 100644
--- a/src/core/cfuns.c
+++ b/src/core/cfuns.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/compile.c b/src/core/compile.c
index 3ceb04fb..ea81a660 100644
--- a/src/core/compile.c
+++ b/src/core/compile.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/compile.h b/src/core/compile.h
index b5111f4a..197f034c 100644
--- a/src/core/compile.h
+++ b/src/core/compile.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/corelib.c b/src/core/corelib.c
index cf1d9ab5..52d445f3 100644
--- a/src/core/corelib.c
+++ b/src/core/corelib.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/debug.c b/src/core/debug.c
index 2cbd6aa3..6e03f78d 100644
--- a/src/core/debug.c
+++ b/src/core/debug.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/emit.c b/src/core/emit.c
index 59d447a4..47127800 100644
--- a/src/core/emit.c
+++ b/src/core/emit.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/emit.h b/src/core/emit.h
index 2fdf0d47..64a6a268 100644
--- a/src/core/emit.h
+++ b/src/core/emit.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/ev.c b/src/core/ev.c
index e51fee80..c6e99d6b 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -112,6 +112,13 @@ typedef struct {
     JanetHandle write_pipe;
 } JanetEVThreadInit;
 
+/* Structure used to initialize threads that run timeouts */
+typedef struct {
+    double sec;
+    JanetVM *vm;
+    JanetFiber *fiber;
+} JanetThreadedTimeout;
+
 #define JANET_MAX_Q_CAPACITY 0x7FFFFFF
 
 static void janet_q_init(JanetQueue *q) {
@@ -623,6 +630,7 @@ void janet_addtimeout(double sec) {
     to.curr_fiber = NULL;
     to.sched_id = fiber->sched_id;
     to.is_error = 1;
+    to.has_worker = 0;
     add_timeout(to);
 }
 
@@ -635,9 +643,54 @@ void janet_addtimeout_nil(double sec) {
     to.curr_fiber = NULL;
     to.sched_id = fiber->sched_id;
     to.is_error = 0;
+    to.has_worker = 0;
     add_timeout(to);
 }
 
+#ifdef JANET_WINDOWS
+static VOID CALLBACK janet_timeout_stop(ULONG_PTR ptr) {
+    UNREFERENCED_PARAMETER(ptr);
+    ExitThread(0);
+}
+#endif
+
+static void janet_timeout_cb(JanetEVGenericMessage msg) {
+    (void) msg;
+    janet_interpreter_interrupt_handled(&janet_vm);
+}
+
+#ifdef JANET_WINDOWS
+static DWORD WINAPI janet_timeout_body(LPVOID ptr) {
+    JanetThreadedTimeout tto = *(JanetThreadedTimeout *)ptr;
+    janet_free(ptr);
+    SleepEx((DWORD)(tto.sec * 1000), TRUE);
+    if (janet_fiber_can_resume(tto.fiber)) {
+        janet_interpreter_interrupt(tto.vm);
+        JanetEVGenericMessage msg = {0};
+        janet_ev_post_event(tto.vm, janet_timeout_cb, msg);
+    }
+    return 0;
+}
+#else
+static void *janet_timeout_body(void *ptr) {
+    JanetThreadedTimeout tto = *(JanetThreadedTimeout *)ptr;
+    janet_free(ptr);
+    struct timespec ts;
+    ts.tv_sec = (time_t) tto.sec;
+    ts.tv_nsec = (tto.sec <= UINT32_MAX)
+                 ? (long)((tto.sec - ((uint32_t)tto.sec)) * 1000000000)
+                 : 0;
+    nanosleep(&ts, &ts);
+    if (janet_fiber_can_resume(tto.fiber)) {
+        janet_interpreter_interrupt(tto.vm);
+        JanetEVGenericMessage msg = {0};
+        janet_ev_post_event(tto.vm, janet_timeout_cb, msg);
+    }
+    return NULL;
+}
+#endif
+
+
 void janet_ev_inc_refcount(void) {
     janet_atomic_inc(&janet_vm.listener_count);
 }
@@ -1431,6 +1484,17 @@ JanetFiber *janet_loop1(void) {
         while ((has_timeout = peek_timeout(&to))) {
             if (to.curr_fiber != NULL) {
                 if (!janet_fiber_can_resume(to.curr_fiber)) {
+                    if (to.has_worker) {
+#ifdef JANET_WINDOWS
+                        QueueUserAPC(janet_timeout_stop, to.worker, 0);
+                        WaitForSingleObject(to.worker, INFINITE);
+                        CloseHandle(to.worker);
+#else
+                        pthread_cancel(to.worker);
+                        void *res;
+                        pthread_join(to.worker, &res);
+#endif
+                    }
                     janet_table_remove(&janet_vm.active_tasks, janet_wrap_fiber(to.curr_fiber));
                     pop_timeout(0);
                     continue;
@@ -3103,26 +3167,53 @@ JANET_CORE_FN(cfun_ev_sleep,
 }
 
 JANET_CORE_FN(cfun_ev_deadline,
-              "(ev/deadline sec &opt tocancel tocheck)",
-              "Schedules the event loop to try to cancel the `tocancel` "
-              "task as with `ev/cancel`. After `sec` seconds, the event "
-              "loop will attempt cancellation of `tocancel` if the "
-              "`tocheck` fiber is resumable. `sec` is a number that can "
-              "have a fractional part. `tocancel` defaults to "
-              "`(fiber/root)`, but if specified, must be a task (root "
-              "fiber). `tocheck` defaults to `(fiber/current)`, but if "
-              "specified, should be a fiber. Returns `tocancel` "
-              "immediately.") {
-    janet_arity(argc, 1, 3);
+              "(ev/deadline sec &opt tocancel tocheck intr?)",
+              "Schedules the event loop to try to cancel the `tocancel` task as with `ev/cancel`. "
+              "After `sec` seconds, the event loop will attempt cancellation of `tocancel` if the "
+              "`tocheck` fiber is resumable. `sec` is a number that can have a fractional part. "
+              "`tocancel` defaults to `(fiber/root)`, but if specified, must be a task (root "
+              "fiber). `tocheck` defaults to `(fiber/current)`, but if specified, must be a fiber. "
+              "Returns `tocancel` immediately. If `interrupt?` is set to true, will create a "
+              "background thread to try to interrupt the VM if the timeout expires.") {
+    janet_arity(argc, 1, 4);
     double sec = janet_getnumber(argv, 0);
+    sec = (sec < 0) ? 0 : sec;
     JanetFiber *tocancel = janet_optfiber(argv, argc, 1, janet_vm.root_fiber);
     JanetFiber *tocheck = janet_optfiber(argv, argc, 2, janet_vm.fiber);
+    int use_interrupt = janet_optboolean(argv, argc, 3, 0);
     JanetTimeout to;
     to.when = ts_delta(ts_now(), sec);
     to.fiber = tocancel;
     to.curr_fiber = tocheck;
     to.is_error = 0;
     to.sched_id = to.fiber->sched_id;
+    if (use_interrupt) {
+        JanetThreadedTimeout *tto = janet_malloc(sizeof(JanetThreadedTimeout));
+        if (NULL == tto) {
+            JANET_OUT_OF_MEMORY;
+        }
+        tto->sec = sec;
+        tto->vm = &janet_vm;
+        tto->fiber = tocheck;
+#ifdef JANET_WINDOWS
+        HANDLE worker = CreateThread(NULL, 0, janet_timeout_body, tto, 0, NULL);
+        if (NULL == worker) {
+            janet_free(tto);
+            janet_panic("failed to create thread");
+        }
+#else
+        pthread_t worker;
+        int err = pthread_create(&worker, NULL, janet_timeout_body, tto);
+        if (err) {
+            janet_free(tto);
+            janet_panicf("%s", janet_strerror(err));
+        }
+#endif
+        to.has_worker = 1;
+        to.worker = worker;
+    } else {
+        to.has_worker = 0;
+    }
     add_timeout(to);
     return janet_wrap_fiber(tocancel);
 }
diff --git a/src/core/features.h b/src/core/features.h
index 591c2bad..d799880a 100644
--- a/src/core/features.h
+++ b/src/core/features.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/ffi.c b/src/core/ffi.c
index c95642ad..f14ff2f7 100644
--- a/src/core/ffi.c
+++ b/src/core/ffi.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
@@ -1686,7 +1686,7 @@ JANET_CORE_FN(cfun_ffi_buffer_write,
     JanetFFIType type = decode_ffi_type(argv[0]);
     uint32_t el_size = (uint32_t) type_size(type);
     JanetBuffer *buffer = janet_optbuffer(argv, argc, 2, el_size);
-    int32_t index = janet_optnat(argv, argc, 3, 0);
+    int32_t index = janet_optnat(argv, argc, 3, buffer->count);
     int32_t old_count = buffer->count;
     if (index > old_count) janet_panic("index out of bounds");
     buffer->count = index;
diff --git a/src/core/fiber.c b/src/core/fiber.c
index c1a0b2f6..72d8f2de 100644
--- a/src/core/fiber.c
+++ b/src/core/fiber.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/fiber.h b/src/core/fiber.h
index a83610e4..8626e89c 100644
--- a/src/core/fiber.h
+++ b/src/core/fiber.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/filewatch.c b/src/core/filewatch.c
index f515feb0..85f1d266 100644
--- a/src/core/filewatch.c
+++ b/src/core/filewatch.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/gc.c b/src/core/gc.c
index 942cd272..038c9106 100644
--- a/src/core/gc.c
+++ b/src/core/gc.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/gc.h b/src/core/gc.h
index c7502b61..37318eee 100644
--- a/src/core/gc.h
+++ b/src/core/gc.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/inttypes.c b/src/core/inttypes.c
index 855793d7..db0d2b28 100644
--- a/src/core/inttypes.c
+++ b/src/core/inttypes.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose & contributors
+* Copyright (c) 2025 Calvin Rose & contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/io.c b/src/core/io.c
index 0f6703e9..4d45caba 100644
--- a/src/core/io.c
+++ b/src/core/io.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/marsh.c b/src/core/marsh.c
index 58433095..13b3344b 100644
--- a/src/core/marsh.c
+++ b/src/core/marsh.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/math.c b/src/core/math.c
index f27b6ffd..400ed7e4 100644
--- a/src/core/math.c
+++ b/src/core/math.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/net.c b/src/core/net.c
index 21f4bdb1..e9254027 100644
--- a/src/core/net.c
+++ b/src/core/net.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose and contributors.
+* Copyright (c) 2025 Calvin Rose and contributors.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/os.c b/src/core/os.c
index c814ef3a..fe1184e9 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose and contributors.
+* Copyright (c) 2025 Calvin Rose and contributors.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
@@ -541,11 +541,12 @@ static void janet_proc_wait_cb(JanetEVGenericMessage args) {
         proc->flags &= ~JANET_PROC_WAITING;
         janet_gcunroot(janet_wrap_abstract(proc));
         janet_gcunroot(janet_wrap_fiber(args.fiber));
-        if ((status != 0) && (proc->flags & JANET_PROC_ERROR_NONZERO)) {
-            JanetString s = janet_formatc("command failed with non-zero exit code %d", status);
-            janet_cancel(args.fiber, janet_wrap_string(s));
-        } else {
-            if (janet_fiber_can_resume(args.fiber)) {
+        uint32_t sched_id = (uint32_t) args.argi;
+        if (janet_fiber_can_resume(args.fiber) && args.fiber->sched_id == sched_id) {
+            if ((status != 0) && (proc->flags & JANET_PROC_ERROR_NONZERO)) {
+                JanetString s = janet_formatc("command failed with non-zero exit code %d", status);
+                janet_cancel(args.fiber, janet_wrap_string(s));
+            } else {
                 janet_schedule(args.fiber, janet_wrap_integer(status));
             }
         }
@@ -603,6 +604,7 @@ os_proc_wait_impl(JanetProc *proc) {
     memset(&targs, 0, sizeof(targs));
     targs.argp = proc;
     targs.fiber = janet_root_fiber();
+    targs.argi = (uint32_t) targs.fiber->sched_id;
     janet_gcroot(janet_wrap_abstract(proc));
     janet_gcroot(janet_wrap_fiber(targs.fiber));
     janet_ev_threaded_call(janet_proc_wait_subr, targs, janet_proc_wait_cb);
@@ -629,16 +631,15 @@ os_proc_wait_impl(JanetProc *proc) {
 
 JANET_CORE_FN(os_proc_wait,
               "(os/proc-wait proc)",
-              "Suspend the current fiber until the subprocess completes. Returns the subprocess return code. "
-              "os/proc-wait cannot be called twice on the same process. If `ev/with-deadline` cancels `os/proc-wait` "
-              "with an error or os/proc-wait is cancelled with any error caused by anything else, os/proc-wait still "
-              "finishes in the background. Only after os/proc-wait finishes, a process is cleaned up by the operating "
-              "system. Thus, a process becomes a zombie process if os/proc-wait is not called.") {
+              "Suspend the current fiber until the subprocess `proc` completes. Once `proc` "
+              "completes, return the exit code of `proc`. If called more than once on the same "
+              "core/process value, will raise an error. When creating subprocesses using "
+              "`os/spawn`, this function should be called on the returned value to avoid zombie "
+              "processes.") {
     janet_fixarity(argc, 1);
     JanetProc *proc = janet_getabstract(argv, 0, &ProcAT);
 #ifdef JANET_EV
     os_proc_wait_impl(proc);
-    return janet_wrap_nil();
 #else
     return os_proc_wait_impl(proc);
 #endif
@@ -743,12 +744,13 @@ static int get_signal_kw(const Janet *argv, int32_t n) {
 
 JANET_CORE_FN(os_proc_kill,
               "(os/proc-kill proc &opt wait signal)",
-              "Kill a subprocess by sending SIGKILL to it on posix systems, or by closing the process "
-              "handle on windows. If os/proc-wait already finished for proc, os/proc-kill raises an error. After "
-              "sending signal to proc, if `wait` is truthy, will wait for the process to finish and return the exit "
-              "code by calling os/proc-wait. Otherwise, returns `proc`. If signal is specified, send it instead. "
-              "Signal keywords are named after their C counterparts but in lowercase with the leading `SIG` stripped. "
-              "Signals are ignored on windows.") {
+              "Kill the subprocess `proc` by sending SIGKILL to it on POSIX systems, or by closing "
+              "the process handle on Windows. If `proc` has already completed, raise an error. If "
+              "`wait` is truthy, will wait for `proc` to complete and return the exit code (this "
+              "will raise an error if `proc` is being waited for). Otherwise, return `proc`. If "
+              "`signal` is provided, send it instead of SIGKILL. Signal keywords are named after "
+              "their C counterparts but in lowercase with the leading SIG stripped. `signal` is "
+              "ignored on Windows.") {
     janet_arity(argc, 1, 3);
     JanetProc *proc = janet_getabstract(argv, 0, &ProcAT);
     if (proc->flags & JANET_PROC_WAITED) {
@@ -776,7 +778,6 @@ JANET_CORE_FN(os_proc_kill,
     if (argc > 1 && janet_truthy(argv[1])) {
 #ifdef JANET_EV
         os_proc_wait_impl(proc);
-        return janet_wrap_nil();
 #else
         return os_proc_wait_impl(proc);
 #endif
@@ -787,9 +788,9 @@ JANET_CORE_FN(os_proc_kill,
 
 JANET_CORE_FN(os_proc_close,
               "(os/proc-close proc)",
-              "Close pipes created by `os/spawn` if they have not been closed. Then, if os/proc-wait was not already "
-              "called on proc, os/proc-wait is called on it, and it returns the exit code returned by os/proc-wait. "
-              "Otherwise, returns nil.") {
+              "Close pipes created for subprocess `proc` by `os/spawn` if they have not been "
+              "closed. Then, if `proc` is not being waited for, wait. If this function waits, when "
+              "`proc` completes, return the exit code of `proc`. Otherwise, return nil.") {
     janet_fixarity(argc, 1);
     JanetProc *proc = janet_getabstract(argv, 0, &ProcAT);
 #ifdef JANET_EV
@@ -807,7 +808,6 @@ JANET_CORE_FN(os_proc_close,
     }
 #ifdef JANET_EV
     os_proc_wait_impl(proc);
-    return janet_wrap_nil();
 #else
     return os_proc_wait_impl(proc);
 #endif
@@ -1268,9 +1268,6 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, JanetExecuteMode mode) {
 
     /* exec mode */
     if (mode == JANET_EXECUTE_EXEC) {
-#ifdef JANET_WINDOWS
-        janet_panic("not supported on windows");
-#else
         int status;
         if (!use_environ) {
             environ = envp;
@@ -1283,7 +1280,6 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, JanetExecuteMode mode) {
             }
         } while (status == -1 && errno == EINTR);
         janet_panicf("%p: %s", cargv[0], janet_strerror(errno ? errno : ENOENT));
-#endif
     }
 
     /* Use posix_spawn to spawn new process */
@@ -1384,45 +1380,56 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, JanetExecuteMode mode) {
 
 JANET_CORE_FN(os_execute,
               "(os/execute args &opt flags env)",
-              "Execute a program on the system and pass it string arguments. `flags` "
-              "is a keyword that modifies how the program will execute.\n"
-              "* :e - enables passing an environment to the program. Without :e, the "
+              "Execute a program on the system and return the exit code. `args` is an array/tuple "
+              "of strings. The first string is the name of the program and the remainder are "
+              "arguments passed to the program. `flags` is a keyword made from the following "
+              "characters that modifies how the program executes:\n"
+              "* :e - enables passing an environment to the program. Without 'e', the "
               "current environment is inherited.\n"
-              "* :p - allows searching the current PATH for the binary to execute. "
-              "Without this flag, binaries must use absolute paths.\n"
-              "* :x - raise error if exit code is non-zero.\n"
-              "* :d - Don't try and terminate the process on garbage collection (allow spawning zombies).\n"
-              "`env` is a table or struct mapping environment variables to values. It can also "
-              "contain the keys :in, :out, and :err, which allow redirecting stdio in the subprocess. "
-              ":in, :out, and :err should be core/file values or core/stream values. core/file values and core/stream "
-              "values passed to :in, :out, and :err should be closed manually because os/execute doesn't close them. "
-              "Returns the exit code of the program.") {
+              "* :p - allows searching the current PATH for the program to execute. "
+              "Without this flag, the first element of `args` must be an absolute path.\n"
+              "* :x - raises error if exit code is non-zero.\n"
+              "* :d - prevents the garbage collector terminating the program (if still running) "
+              "and calling the equivalent of `os/proc-wait` (allows zombie processes).\n"
+              "`env` is a table/struct mapping environment variables to values. It can also "
+              "contain the keys :in, :out, and :err, which allow redirecting stdio in the "
+              "subprocess. :in, :out, and :err should be core/file or core/stream values. "
+              "If core/stream values are used, the caller is responsible for ensuring pipes do not "
+              "cause the program to block and deadlock.") {
     return os_execute_impl(argc, argv, JANET_EXECUTE_EXECUTE);
 }
 
 JANET_CORE_FN(os_spawn,
               "(os/spawn args &opt flags env)",
-              "Execute a program on the system and return a handle to the process. Otherwise, takes the "
-              "same arguments as `os/execute`. Does not wait for the process. For each of the :in, :out, and :err keys "
-              "of the `env` argument, one can also pass in the keyword `:pipe` to get streams for standard IO of the "
-              "subprocess that can be read from and written to. The returned value `proc` has the fields :in, :out, "
-              ":err, and the additional field :pid on unix-like platforms. `(os/proc-wait proc)` must be called to "
-              "rejoin the subprocess. After `(os/proc-wait proc)` finishes, proc gains a new field, :return-code. "
-              "If :x flag is passed to os/spawn, non-zero exit code will cause os/proc-wait to raise an error. "
-              "If pipe streams created with :pipe keyword are not closed in time, janet can run out of file "
-              "descriptors. They can be closed individually, or `os/proc-close` can close all pipe streams on proc. "
-              "If pipe streams aren't read before `os/proc-wait` finishes, then pipe buffers become full, and the "
-              "process cannot finish because the process cannot print more on pipe buffers which are already full. "
-              "If the process cannot finish, os/proc-wait cannot finish, either.") {
+              "Execute a program on the system and return a core/process value representing the "
+              "spawned subprocess. Takes the same arguments as `os/execute` but does not wait for "
+              "the subprocess to complete. Unlike `os/execute`, the value `:pipe` can be used for "
+              ":in, :out and :err keys in `env`. If used, the returned core/process will have a "
+              "writable stream in the :in field and readable streams in the :out and :err fields. "
+              "On non-Windows systems, the subprocess PID will be in the :pid field. The caller is "
+              "responsible for waiting on the process (e.g. by calling `os/proc-wait` on the "
+              "returned core/process value) to avoid creating zombie process. After the subprocess "
+              "completes, the exit value is in the :return-code field. If `flags` includes 'x', a "
+              "non-zero exit code will cause a waiting fiber to raise an error. The use of "
+              "`:pipe` may fail if there are too many active file descriptors. The caller is "
+              "responsible for closing pipes created by `:pipe` (either individually or using "
+              "`os/proc-close`). Similar to `os/execute`, the caller is responsible for ensuring "
+              "pipes do not cause the program to block and deadlock.") {
     return os_execute_impl(argc, argv, JANET_EXECUTE_SPAWN);
 }
 
 JANET_CORE_FN(os_posix_exec,
               "(os/posix-exec args &opt flags env)",
               "Use the execvpe or execve system calls to replace the current process with an interface similar to os/execute. "
-              "However, instead of creating a subprocess, the current process is replaced. Is not supported on windows, and "
+              "However, instead of creating a subprocess, the current process is replaced. Is not supported on Windows, and "
               "does not allow redirection of stdio.") {
+#ifdef JANET_WINDOWS
+    (void) argc;
+    (void) argv;
+    janet_panic("not supported on Windows");
+#else
     return os_execute_impl(argc, argv, JANET_EXECUTE_EXEC);
+#endif
 }
 
 JANET_CORE_FN(os_posix_fork,
@@ -1433,7 +1440,7 @@ JANET_CORE_FN(os_posix_fork,
     janet_fixarity(argc, 0);
     (void) argv;
 #ifdef JANET_WINDOWS
-    janet_panic("not supported");
+    janet_panic("not supported on Windows");
 #else
     pid_t result;
     do {
@@ -1880,7 +1887,6 @@ JANET_CORE_FN(os_mktime,
         /* utc time */
 #ifdef JANET_NO_UTC_MKTIME
         janet_panic("os/mktime UTC not supported on this platform");
-        return janet_wrap_nil();
 #else
         t = timegm(&t_info);
 #endif
@@ -1947,8 +1953,7 @@ JANET_CORE_FN(os_link,
 #ifdef JANET_WINDOWS
     (void) argc;
     (void) argv;
-    janet_panic("os/link not supported on Windows");
-    return janet_wrap_nil();
+    janet_panic("not supported on Windows");
 #else
     const char *oldpath = janet_getcstring(argv, 0);
     const char *newpath = janet_getcstring(argv, 1);
@@ -1966,8 +1971,7 @@ JANET_CORE_FN(os_symlink,
 #ifdef JANET_WINDOWS
     (void) argc;
     (void) argv;
-    janet_panic("os/symlink not supported on Windows");
-    return janet_wrap_nil();
+    janet_panic("not supported on Windows");
 #else
     const char *oldpath = janet_getcstring(argv, 0);
     const char *newpath = janet_getcstring(argv, 1);
@@ -2069,8 +2073,7 @@ JANET_CORE_FN(os_readlink,
 #ifdef JANET_WINDOWS
     (void) argc;
     (void) argv;
-    janet_panic("os/readlink not supported on Windows");
-    return janet_wrap_nil();
+    janet_panic("not supported on Windows");
 #else
     static char buffer[PATH_MAX];
     const char *path = janet_getcstring(argv, 0);
@@ -2326,7 +2329,6 @@ static Janet os_stat_or_lstat(int do_lstat, int32_t argc, Janet *argv) {
             return sg->fn(&st);
         }
         janet_panicf("unexpected keyword %v", janet_wrap_keyword(key));
-        return janet_wrap_nil();
     }
 }
 
diff --git a/src/core/parse.c b/src/core/parse.c
index c9177316..5b5ffff8 100644
--- a/src/core/parse.c
+++ b/src/core/parse.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/pp.c b/src/core/pp.c
index 74022b8f..0c9e81ce 100644
--- a/src/core/pp.c
+++ b/src/core/pp.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/regalloc.c b/src/core/regalloc.c
index 7bc1d8ca..ef8768eb 100644
--- a/src/core/regalloc.c
+++ b/src/core/regalloc.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/regalloc.h b/src/core/regalloc.h
index bd1e76e6..ca6c833e 100644
--- a/src/core/regalloc.h
+++ b/src/core/regalloc.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/run.c b/src/core/run.c
index 9942f07b..0be7f6db 100644
--- a/src/core/run.c
+++ b/src/core/run.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/specials.c b/src/core/specials.c
index b9d79f68..1a17257e 100644
--- a/src/core/specials.c
+++ b/src/core/specials.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/state.c b/src/core/state.c
index 003dd796..3d84dcd1 100644
--- a/src/core/state.c
+++ b/src/core/state.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/state.h b/src/core/state.h
index d121f559..918c1ade 100644
--- a/src/core/state.h
+++ b/src/core/state.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
@@ -27,7 +27,9 @@
 #include <stdint.h>
 
 #ifdef JANET_EV
-#ifndef JANET_WINDOWS
+#ifdef JANET_WINDOWS
+#include <windows.h>
+#else
 #include <pthread.h>
 #endif
 #endif
@@ -53,13 +55,21 @@ typedef struct {
     void *data;
 } JanetQueue;
 
+#ifdef JANET_EV
 typedef struct {
     JanetTimestamp when;
     JanetFiber *fiber;
     JanetFiber *curr_fiber;
     uint32_t sched_id;
     int is_error;
+    int has_worker;
+#ifdef JANET_WINDOWS
+    HANDLE worker;
+#else
+    pthread_t worker;
+#endif
 } JanetTimeout;
+#endif
 
 /* Registry table for C functions - contains metadata that can
  * be looked up by cfunction pointer. All strings here are pointing to
diff --git a/src/core/string.c b/src/core/string.c
index 6a67482c..24181cbc 100644
--- a/src/core/string.c
+++ b/src/core/string.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/strtod.c b/src/core/strtod.c
index 33857027..3873a6fd 100644
--- a/src/core/strtod.c
+++ b/src/core/strtod.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/struct.c b/src/core/struct.c
index 2e4be627..1b1cad7b 100644
--- a/src/core/struct.c
+++ b/src/core/struct.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/symcache.c b/src/core/symcache.c
index 4d1af72c..68ddf8bf 100644
--- a/src/core/symcache.c
+++ b/src/core/symcache.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/symcache.h b/src/core/symcache.h
index ea55627e..5e3fbbe0 100644
--- a/src/core/symcache.h
+++ b/src/core/symcache.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/table.c b/src/core/table.c
index 229d8fa3..910ceba2 100644
--- a/src/core/table.c
+++ b/src/core/table.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/tuple.c b/src/core/tuple.c
index 97aa483f..7c004751 100644
--- a/src/core/tuple.c
+++ b/src/core/tuple.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/util.c b/src/core/util.c
index 9ad64c56..db65deb2 100644
--- a/src/core/util.c
+++ b/src/core/util.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/util.h b/src/core/util.h
index a2da921a..4e16f5e0 100644
--- a/src/core/util.h
+++ b/src/core/util.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
@@ -205,9 +205,9 @@ int janet_make_pipe(JanetHandle handles[2], int mode);
 #ifdef JANET_FILEWATCH
 void janet_lib_filewatch(JanetTable *env);
 #endif
+#endif
 #ifdef JANET_FFI
 void janet_lib_ffi(JanetTable *env);
 #endif
-#endif
 
 #endif
diff --git a/src/core/value.c b/src/core/value.c
index 74486371..b278a1bc 100644
--- a/src/core/value.c
+++ b/src/core/value.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/vector.c b/src/core/vector.c
index 4fe49572..64f1e780 100644
--- a/src/core/vector.c
+++ b/src/core/vector.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/vector.h b/src/core/vector.h
index 9cf90387..5aa24c13 100644
--- a/src/core/vector.h
+++ b/src/core/vector.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/core/vm.c b/src/core/vm.c
index 4fe179d3..6ad79053 100644
--- a/src/core/vm.c
+++ b/src/core/vm.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
@@ -798,14 +798,14 @@ static JanetSignal run_vm(JanetFiber *fiber, Janet in) {
     vm_pcnext();
 
     VM_OP(JOP_JUMP)
-    pc += DS;
     vm_maybe_auto_suspend(DS <= 0);
+    pc += DS;
     vm_next();
 
     VM_OP(JOP_JUMP_IF)
     if (janet_truthy(stack[A])) {
-        pc += ES;
         vm_maybe_auto_suspend(ES <= 0);
+        pc += ES;
     } else {
         pc++;
     }
@@ -815,15 +815,15 @@ static JanetSignal run_vm(JanetFiber *fiber, Janet in) {
     if (janet_truthy(stack[A])) {
         pc++;
     } else {
-        pc += ES;
         vm_maybe_auto_suspend(ES <= 0);
+        pc += ES;
     }
     vm_next();
 
     VM_OP(JOP_JUMP_IF_NIL)
     if (janet_checktype(stack[A], JANET_NIL)) {
-        pc += ES;
         vm_maybe_auto_suspend(ES <= 0);
+        pc += ES;
     } else {
         pc++;
     }
@@ -833,8 +833,8 @@ static JanetSignal run_vm(JanetFiber *fiber, Janet in) {
     if (janet_checktype(stack[A], JANET_NIL)) {
         pc++;
     } else {
-        pc += ES;
         vm_maybe_auto_suspend(ES <= 0);
+        pc += ES;
     }
     vm_next();
 
diff --git a/src/core/wrap.c b/src/core/wrap.c
index 98214fe0..c4fc1d16 100644
--- a/src/core/wrap.c
+++ b/src/core/wrap.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/include/janet.h b/src/include/janet.h
index 988e8016..de82b5fb 100644
--- a/src/include/janet.h
+++ b/src/include/janet.h
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/src/mainclient/shell.c b/src/mainclient/shell.c
index 3b20f629..3d95ee2d 100644
--- a/src/mainclient/shell.c
+++ b/src/mainclient/shell.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/test/amalg/main.c b/test/amalg/main.c
index 39d89317..3bcc688b 100644
--- a/test/amalg/main.c
+++ b/test/amalg/main.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-array.janet b/test/suite-array.janet
index f0fecbaa..13e2407d 100644
--- a/test/suite-array.janet
+++ b/test/suite-array.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-asm.janet b/test/suite-asm.janet
index e435094d..075fe4e1 100644
--- a/test/suite-asm.janet
+++ b/test/suite-asm.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-boot.janet b/test/suite-boot.janet
index ec7c4133..c1fb8460 100644
--- a/test/suite-boot.janet
+++ b/test/suite-boot.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-buffer.janet b/test/suite-buffer.janet
index e5de3f86..45d077b9 100644
--- a/test/suite-buffer.janet
+++ b/test/suite-buffer.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2024 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-bundle.janet b/test/suite-bundle.janet
index f860c1fd..0d228cc9 100644
--- a/test/suite-bundle.janet
+++ b/test/suite-bundle.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2024 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-capi.janet b/test/suite-capi.janet
index 52f05433..dfa86fc0 100644
--- a/test/suite-capi.janet
+++ b/test/suite-capi.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-cfuns.janet b/test/suite-cfuns.janet
index d06323bf..3e36c3f7 100644
--- a/test/suite-cfuns.janet
+++ b/test/suite-cfuns.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-compile.janet b/test/suite-compile.janet
index e52c4057..204a91f8 100644
--- a/test/suite-compile.janet
+++ b/test/suite-compile.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-corelib.janet b/test/suite-corelib.janet
index 119ec768..d2a5d4d5 100644
--- a/test/suite-corelib.janet
+++ b/test/suite-corelib.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-debug.janet b/test/suite-debug.janet
index 3ed87e46..e0d8793d 100644
--- a/test/suite-debug.janet
+++ b/test/suite-debug.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-ev.janet b/test/suite-ev.janet
index c773e960..cf040e2c 100644
--- a/test/suite-ev.janet
+++ b/test/suite-ev.janet
@@ -526,4 +526,32 @@
 (assert (= maxconn connect-count))
 (:close s)
 
+# Cancel os/proc-wait with ev/deadline
+(let [p (os/spawn [;run janet "-e" "(os/sleep 4)"] :p)]
+  (var terminated-normally false)
+  (assert-error "deadline expired"
+                (ev/with-deadline 0.01
+                  (os/proc-wait p)
+                  (print "uhoh")
+                  (set terminated-normally true)))
+  (assert (not terminated-normally) "early termination failure")
+  # Without this kill, janet will wait the full 4 seconds for the subprocess to complete before exiting.
+  (assert-no-error "kill proc after wait failed" (os/proc-kill p)))
+
+# Cancel os/proc-wait with ev/deadline 2
+(let [p (os/spawn [;run janet "-e" "(os/sleep 0.1)"] :p)]
+  (var terminated-normally false)
+  (assert-error "deadline expired"
+                (ev/with-deadline 0.05
+                  (os/proc-wait p)
+                  (print "uhoh")
+                  (set terminated-normally true)))
+  (assert (not terminated-normally) "early termination failure 2")
+  (ev/sleep 0.15)
+  (assert (not terminated-normally) "early termination failure 3"))
+
+(let [f (coro (forever :foo))]
+  (ev/deadline 0.01 nil f true)
+  (assert-error "deadline expired" (resume f)))
+
 (end-suite)
diff --git a/test/suite-ffi.janet b/test/suite-ffi.janet
index 6305651e..c6237736 100644
--- a/test/suite-ffi.janet
+++ b/test/suite-ffi.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose & contributors
+# Copyright (c) 2025 Calvin Rose & contributors
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
@@ -55,4 +55,11 @@
 (compwhen has-ffi
   (assert-error "bad struct issue #1512" (ffi/struct :void)))
 
+(compwhen has-ffi
+  (def buf @"")
+  (ffi/write :u8 10 buf)
+  (assert (= 1 (length buf)))
+  (ffi/write :u8 10 buf)
+  (assert (= 2 (length buf))))
+
 (end-suite)
diff --git a/test/suite-filewatch.janet b/test/suite-filewatch.janet
index 90bb82b9..9c3f7404 100644
--- a/test/suite-filewatch.janet
+++ b/test/suite-filewatch.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2024 Calvin Rose & contributors
+# Copyright (c) 2025 Calvin Rose & contributors
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-inttypes.janet b/test/suite-inttypes.janet
index 67272130..91b38590 100644
--- a/test/suite-inttypes.janet
+++ b/test/suite-inttypes.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose & contributors
+# Copyright (c) 2025 Calvin Rose & contributors
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-io.janet b/test/suite-io.janet
index 826ae755..726b7aa4 100644
--- a/test/suite-io.janet
+++ b/test/suite-io.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose & contributors
+# Copyright (c) 2025 Calvin Rose & contributors
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-marsh.janet b/test/suite-marsh.janet
index 1bcfb0d5..9defbc55 100644
--- a/test/suite-marsh.janet
+++ b/test/suite-marsh.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-math.janet b/test/suite-math.janet
index 235ecc43..58b4ff18 100644
--- a/test/suite-math.janet
+++ b/test/suite-math.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-os.janet b/test/suite-os.janet
index c4d2bda6..40e62bfd 100644
--- a/test/suite-os.janet
+++ b/test/suite-os.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-parse.janet b/test/suite-parse.janet
index 3cf8b595..1cb3c71a 100644
--- a/test/suite-parse.janet
+++ b/test/suite-parse.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-peg.janet b/test/suite-peg.janet
index 59e9353b..cf7e86d6 100644
--- a/test/suite-peg.janet
+++ b/test/suite-peg.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-pp.janet b/test/suite-pp.janet
index 153cff09..4030d64f 100644
--- a/test/suite-pp.janet
+++ b/test/suite-pp.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose & contributors
+# Copyright (c) 2025 Calvin Rose & contributors
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-specials.janet b/test/suite-specials.janet
index b6fdb078..edabf8c3 100644
--- a/test/suite-specials.janet
+++ b/test/suite-specials.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-string.janet b/test/suite-string.janet
index 43774f2d..49c67120 100644
--- a/test/suite-string.janet
+++ b/test/suite-string.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-strtod.janet b/test/suite-strtod.janet
index 888123fe..d14985b9 100644
--- a/test/suite-strtod.janet
+++ b/test/suite-strtod.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-struct.janet b/test/suite-struct.janet
index 32f6e9b4..3178a9e2 100644
--- a/test/suite-struct.janet
+++ b/test/suite-struct.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-symcache.janet b/test/suite-symcache.janet
index 8ad6d3a7..29b6c541 100644
--- a/test/suite-symcache.janet
+++ b/test/suite-symcache.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-table.janet b/test/suite-table.janet
index 4234194b..4f954778 100644
--- a/test/suite-table.janet
+++ b/test/suite-table.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-tuple.janet b/test/suite-tuple.janet
index 6a74e9ec..f2010080 100644
--- a/test/suite-tuple.janet
+++ b/test/suite-tuple.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-unknown.janet b/test/suite-unknown.janet
index 9f034612..f35d3ab4 100644
--- a/test/suite-unknown.janet
+++ b/test/suite-unknown.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-value.janet b/test/suite-value.janet
index bbd443a6..16a6d455 100644
--- a/test/suite-value.janet
+++ b/test/suite-value.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/test/suite-vm.janet b/test/suite-vm.janet
index 5fc375a2..e1019379 100644
--- a/test/suite-vm.janet
+++ b/test/suite-vm.janet
@@ -1,4 +1,4 @@
-# Copyright (c) 2023 Calvin Rose
+# Copyright (c) 2025 Calvin Rose
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to
diff --git a/tools/symcharsgen.c b/tools/symcharsgen.c
index e818bf9e..8193cd5c 100644
--- a/tools/symcharsgen.c
+++ b/tools/symcharsgen.c
@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2024 Calvin Rose
+* Copyright (c) 2025 Calvin Rose
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
diff --git a/tools/update_copyright.janet b/tools/update_copyright.janet
new file mode 100644
index 00000000..71fdf611
--- /dev/null
+++ b/tools/update_copyright.janet
@@ -0,0 +1,44 @@
+(def usage (string "usage: janet " (first (dyn :args)) " <last-year> <this-year>"))
+
+(def ignores [".git"])
+(def exts ["LICENSE" "Makefile" ".build" ".c" ".h" ".janet"])
+
+(defn arg [i]
+  (defn bail [] (print usage) (quit))
+  (if-not (= 3 (length (dyn :args)))
+    (bail)
+    (if-let [val (get (dyn :args) i)]
+      val
+      (bail))))
+
+(def oy (arg 1))
+(def ny (arg 2))
+(def od (string "Copyright (c) " oy " Calvin Rose"))
+(def nd (string "Copyright (c) " ny " Calvin Rose"))
+
+(defn join [dir name]
+  (os/realpath (string dir "/" name)))
+
+(defn add-children [dir paths]
+  (loop [name :in (os/dir dir)
+              :unless (has-value? ignores name)]
+   (array/push paths (join dir name))))
+
+(defn ends-in? [exts s]
+  (find (fn [ext] (string/has-suffix? ext s)) exts))
+
+(defn update-disclaimer [path]
+  (if-let [_   (ends-in? exts path)
+           oc  (slurp path)
+           pos (string/find od oc)
+           nc  (string (string/slice oc 0 pos) nd (string/slice oc (+ pos (length od))))]
+    (spit path nc)))
+
+(def cwd (os/cwd))
+(def paths (if (string/has-suffix? "janet" cwd)
+             @[cwd]
+             @[(join cwd "..")]))
+(loop [p :in paths]
+  (if (= :directory ((os/stat p) :mode))
+    (add-children p paths)
+    (update-disclaimer p)))