diff --git a/CHANGELOG.md b/CHANGELOG.md
index a5841598..d9525e96 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,9 @@
 # Changelog
 All notable changes to this project will be documented in this file.
 
+## Unreleased - ???
+- Fix `%j` formatter to print numbers precisely (using the `%.17g` format string to printf).
+
 ## 1.10.1 - 2020-06-18
 - Expose `janet_table_clear` in API.
 - Respect `JANET_NO_PROCESSES` define when building
diff --git a/meson.build b/meson.build
index bcb0c07e..78625ec2 100644
--- a/meson.build
+++ b/meson.build
@@ -20,7 +20,7 @@
 
 project('janet', 'c',
   default_options : ['c_std=c99', 'b_lundef=false', 'default_library=both'],
-  version : '1.10.1')
+  version : '1.10.2')
 
 # Global settings
 janet_path = join_paths(get_option('prefix'), get_option('libdir'), 'janet')
diff --git a/src/conf/janetconf.h b/src/conf/janetconf.h
index dc57b09b..2343666b 100644
--- a/src/conf/janetconf.h
+++ b/src/conf/janetconf.h
@@ -28,9 +28,9 @@
 
 #define JANET_VERSION_MAJOR 1
 #define JANET_VERSION_MINOR 10
-#define JANET_VERSION_PATCH 1
-#define JANET_VERSION_EXTRA ""
-#define JANET_VERSION "1.10.1"
+#define JANET_VERSION_PATCH 2
+#define JANET_VERSION_EXTRA "-dev"
+#define JANET_VERSION "1.10.2-dev"
 
 /* #define JANET_BUILD "local" */
 
diff --git a/src/core/pp.c b/src/core/pp.c
index 6c030b3a..59acba1b 100644
--- a/src/core/pp.c
+++ b/src/core/pp.c
@@ -123,9 +123,6 @@ static void string_description_b(JanetBuffer *buffer, const char *title, void *p
 #undef POINTSIZE
 }
 
-#undef HEX
-#undef BUFSIZE
-
 static void janet_escape_string_impl(JanetBuffer *buffer, const uint8_t *str, int32_t len) {
     janet_buffer_push_u8(buffer, '"');
     for (int32_t i = 0; i < len; ++i) {
@@ -354,12 +351,16 @@ static int print_jdn_one(struct pretty *S, Janet x, int depth) {
     if (depth == 0) return 1;
     switch (janet_type(x)) {
         case JANET_NIL:
-        case JANET_NUMBER:
         case JANET_BOOLEAN:
         case JANET_BUFFER:
         case JANET_STRING:
             janet_description_b(S->buffer, x);
             break;
+        case JANET_NUMBER:
+            janet_buffer_ensure(S->buffer, S->buffer->count + BUFSIZE, 2);
+            int count = snprintf((char *) S->buffer->data + S->buffer->count, BUFSIZE, "%.17g", janet_unwrap_number(x));
+            S->buffer->count += count;
+            break;
         case JANET_SYMBOL:
         case JANET_KEYWORD:
             if (contains_bad_chars(janet_unwrap_keyword(x), janet_type(x) == JANET_SYMBOL)) return 1;
@@ -994,3 +995,6 @@ void janet_buffer_format(
         }
     }
 }
+
+#undef HEX
+#undef BUFSIZE
diff --git a/test/suite8.janet b/test/suite8.janet
index 71f1b0ff..9cd6152f 100644
--- a/test/suite8.janet
+++ b/test/suite8.janet
@@ -307,4 +307,16 @@ neldb\0\0\0\xD8\x05printG\x01\0\xDE\xDE\xDE'\x03\0marshal_tes/\x02
 (assert (:match peg5 "abcabcabcac") "repeat alias 2")
 (assert (not (:match peg5 "abcabc")) "repeat alias 3")
 
+(defn check-jdn [x]
+  (assert (deep= (parse (string/format "%j" x)) x) "round trip jdn"))
+
+(check-jdn 0)
+(check-jdn nil)
+(check-jdn [])
+(check-jdn @[[] [] 1231 9.123123 -123123 0.1231231230001])
+(check-jdn -0.123123123123)
+(check-jdn 12837192371923)
+(check-jdn "a string")
+(check-jdn @"a buffer")
+
 (end-suite)