diff --git a/examples/3sum.janet b/examples/3sum.janet
index f6fe29b2..40fa42d0 100644
--- a/examples/3sum.janet
+++ b/examples/3sum.janet
@@ -5,10 +5,10 @@
   (def solutions @{})
   (def len (length s))
   (for k 0 len
-    (put tab s.k k))
+    (put tab (s k) k))
   (for i 0 len
     (for j 0 len
-      (def k (get tab (- 0 s.i s.j)))
+      (def k (get tab (- 0 (s i) (s j))))
       (when (and k (not= k i) (not= k j) (not= i j))
         (put solutions {i true j true k true} true))))
   (map keys (keys solutions)))
diff --git a/examples/life.janet b/examples/life.janet
index 3402a969..326e57c1 100644
--- a/examples/life.janet
+++ b/examples/life.janet
@@ -16,7 +16,7 @@
   (def cell-set (frequencies state))
   (def neighbor-set (frequencies (mapcat neighbors state)))
   (seq [coord :keys neighbor-set
-         :let [count neighbor-set.coord]
+         :let [count (get neighbor-set coord)]
          :when (or (= count 3) (and (get cell-set coord) (= count 2)))]
       coord))
 
@@ -24,7 +24,7 @@
   "Draw cells in the game of life from (x1, y1) to (x2, y2)"
   [state x1 y1 x2 y2]
   (def cellset @{})
-  (each cell state (set cellset.cell true))
+  (each cell state (put cellset cell true))
   (loop [x :range [x1 (+ 1 x2)]
          :after (print)
          y :range [y1 (+ 1 y2)]]
diff --git a/src/core/compile.c b/src/core/compile.c
index 386ffe34..7a7a9593 100644
--- a/src/core/compile.c
+++ b/src/core/compile.c
@@ -553,7 +553,7 @@ JanetSlot janetc_value(JanetFopts opts, Janet x) {
                 }
                 break;
             case JANET_SYMBOL:
-                ret = janetc_sym_rvalue(opts, janet_unwrap_symbol(x));
+                ret = janetc_resolve(opts.compiler, janet_unwrap_symbol(x));
                 break;
             case JANET_ARRAY:
                 ret = janetc_array(opts, x);
diff --git a/src/core/compile.h b/src/core/compile.h
index 8e69bbe4..bfaa2548 100644
--- a/src/core/compile.h
+++ b/src/core/compile.h
@@ -240,10 +240,4 @@ JanetSlot janetc_cslot(Janet x);
 /* Search for a symbol */
 JanetSlot janetc_resolve(JanetCompiler *c, const uint8_t *sym);
 
-/* Compile a symbol (or mutltisym) when used as an rvalue. */
-JanetSlot janetc_sym_rvalue(JanetFopts opts, const uint8_t *sym);
-
-/* Compile an assignment to a symbol (or multisym) */
-JanetSlot janetc_sym_lvalue(JanetFopts opts, const uint8_t *sym, Janet value);
-
 #endif
diff --git a/src/core/core.janet b/src/core/core.janet
index 22a94f9a..169961a5 100644
--- a/src/core/core.janet
+++ b/src/core/core.janet
@@ -29,14 +29,14 @@
               (array/push modifiers ith))
             (if (< i len) (recur (+ i 1)))))))
     (def start (fstart 0))
-    (def args more.start)
+    (def args (get more start))
     # Add function signature to docstring
     (var index 0)
     (def arglen (length args))
     (def buf (buffer "(" name))
     (while (< index arglen)
       (buffer/push-string buf " ")
-      (string/pretty args.index 4 buf)
+      (string/pretty (get args index) 4 buf)
       (set index (+ index 1)))
     (array/push modifiers (string buf ")\n\n" docstr))
     # Build return value
@@ -186,8 +186,8 @@
   (defn aux [i]
     (def restlen (- (length pairs) i))
     (if (= restlen 0) nil
-      (if (= restlen 1) pairs.i
-        (tuple 'if pairs.i
+      (if (= restlen 1) (get pairs i)
+        (tuple 'if (get pairs i)
                (get pairs (+ i 1))
                (aux (+ i 2))))))
   (aux 0))
@@ -202,8 +202,8 @@
   (defn aux [i]
     (def restlen (- (length pairs) i))
     (if (= restlen 0) nil
-      (if (= restlen 1) pairs.i
-        (tuple 'if (tuple = sym pairs.i)
+      (if (= restlen 1) (get pairs i)
+        (tuple 'if (tuple = sym (get pairs i))
                (get pairs (+ i 1))
                (aux (+ i 2))))))
   (if atm
@@ -254,8 +254,8 @@
   (while (> i 0)
     (-- i)
     (set ret (if (= ret true)
-              forms.i
-              (tuple 'if forms.i ret))))
+              (get forms i)
+              (tuple 'if (get forms i) ret))))
   ret)
 
 (defmacro or
@@ -267,7 +267,7 @@
   (var i len)
   (while (> i 0)
     (-- i)
-    (def fi forms.i)
+    (def fi (get forms i))
     (set ret (if (idempotent? fi)
       (tuple 'if fi fi ret)
       (do
@@ -477,7 +477,7 @@
   (if (zero? len) (error "expected at least 1 binding"))
   (if (odd? len) (error "expected an even number of bindings"))
   (defn aux [i]
-    (def bl bindings.i)
+    (def bl (get bindings i))
     (def br (get bindings (+ 1 i)))
     (if (>= i len)
       tru
@@ -537,7 +537,7 @@
   (when (pos? len)
     (var [ret] args)
     (loop [i :range [0 len]]
-      (def v args.i)
+      (def v (get args i))
       (if (order v ret) (set ret v)))
     ret))
 
@@ -581,17 +581,17 @@
 
     (defn partition
       [a lo hi by]
-      (def pivot a.hi)
+      (def pivot (get a hi))
       (var i lo)
       (loop [j :range [lo hi]]
-        (def aj a.j)
+        (def aj (get a j))
         (when (by aj pivot)
-          (def ai a.i)
-          (set a.i aj)
-          (set a.j ai)
+          (def ai (get a i))
+          (set (a i) aj)
+          (set (a j) ai)
           (++ i)))
-      (set a.hi a.i)
-      (set a.i pivot)
+      (set (a hi) (get a i))
+      (set (a i) pivot)
       i)
 
     (defn sort-help
@@ -627,19 +627,19 @@
   (if (= 0 ninds) (error "expected at least 1 indexed collection"))
   (var limit (length (get inds 0)))
   (loop [i :range [0 ninds]]
-    (def l (length inds.i))
+    (def l (length (get inds i)))
     (if (< l limit) (set limit l)))
   (def [i1 i2 i3 i4] inds)
   (def res (array/new limit))
   (case ninds
-    1 (loop [i :range [0 limit]] (set res.i (f i1.i)))
-    2 (loop [i :range [0 limit]] (set res.i (f i1.i i2.i)))
-    3 (loop [i :range [0 limit]] (set res.i (f i1.i i2.i i3.i)))
-    4 (loop [i :range [0 limit]] (set res.i (f i1.i i2.i i3.i i4.i)))
+    1 (loop [i :range [0 limit]] (set (res i) (f (get i1 i))))
+    2 (loop [i :range [0 limit]] (set (res i) (f (get i1 i) (get i2 i))))
+    3 (loop [i :range [0 limit]] (set (res i) (f (get i1 i) (get i2 i) (get i3 i))))
+    4 (loop [i :range [0 limit]] (set (res i) (f (get i1 i) (get i2 i) (get i3 i) (get i4 i))))
     (loop [i :range [0 limit]]
       (def args (array/new ninds))
-      (loop [j :range [0 ninds]] (set args.j inds.j.i))
-      (set res.i (f ;args))))
+      (loop [j :range [0 ninds]] (set (args j) (get (get inds j) i)))
+      (set (res i) (f ;args))))
   res)
 
 (defn mapcat
@@ -716,7 +716,7 @@
   (var i 0)
   (var going true)
   (while (if (< i len) going)
-    (def item ind.i)
+    (def item (get ind i))
     (if (pred item) (set going false) (++ i)))
   (if going nil i))
 
@@ -839,7 +839,7 @@
 (defn walk-dict [f form]
   (def ret @{})
   (loop [k :keys form]
-    (put ret (f k) (f form.k)))
+    (put ret (f k) (f (get form k))))
   ret)
 
 (defn walk
@@ -916,7 +916,7 @@
   (var n (dec len))
   (def reversed (array/new len))
   (while (>= n 0)
-    (array/push reversed t.n)
+    (array/push reversed (get t n))
     (-- n))
   reversed)
 
@@ -927,7 +927,7 @@ value, one key will be ignored."
   [ds]
   (def ret @{})
   (loop [k :keys ds]
-    (put ret ds.k k))
+    (put ret (get ds k) k))
   ret)
 
 (defn zipcoll
@@ -939,15 +939,15 @@ value, one key will be ignored."
   (def lv (length vals))
   (def len (if (< lk lv) lk lv))
   (loop [i :range [0 len]]
-    (put res keys.i vals.i))
+    (put res (get keys i) (get vals i)))
   res)
 
 (defn update
   "Accepts a key argument and passes its' associated value to a function.
   The key then, is associated to the function's return value"
-  [coll a-key a-function & args]
-  (def old-value coll.a-key)
-  (set coll.a-key (a-function old-value ;args)))
+  [ds key func & args]
+  (def old (get ds key))
+  (set (ds key) (func old ;args)))
 
 (defn merge-into
   "Merges multiple tables/structs into a table. If a key appears in more than one
@@ -956,7 +956,7 @@ value, one key will be ignored."
   [tab & colls]
   (loop [c :in colls
          key :keys c]
-    (set tab.key c.key))
+    (set (tab key) (get c key)))
   tab)
 
 (defn merge
@@ -967,7 +967,7 @@ value, one key will be ignored."
   (def container @{})
   (loop [c :in colls
          key :keys c]
-    (set container.key c.key))
+    (set (container key) (get c key)))
   container)
 
 (defn keys
@@ -986,7 +986,7 @@ value, one key will be ignored."
   (def arr (array/new (length x)))
   (var k (next x nil))
   (while (not= nil k)
-    (array/push arr x.k)
+    (array/push arr (get x k))
     (set k (next x k)))
   arr)
 
@@ -996,7 +996,7 @@ value, one key will be ignored."
   (def arr (array/new (length x)))
   (var k (next x nil))
   (while (not= nil k)
-    (array/push arr (tuple k x.k))
+    (array/push arr (tuple k (get x k)))
     (set k (next x k)))
   arr)
 
@@ -1006,8 +1006,8 @@ value, one key will be ignored."
   (def freqs @{})
   (loop
     [x :in ind]
-    (def n freqs.x)
-    (set freqs.x (if n (+ 1 n) 1)))
+    (def n (get freqs x))
+    (set (freqs x) (if n (+ 1 n) 1)))
   freqs)
 
 (defn interleave
@@ -1020,7 +1020,7 @@ value, one key will be ignored."
     (def len (min ;(map length cols)))
     (loop [i :range [0 len]
            ci :range [0 ncol]]
-        (array/push res cols.ci.i)))
+        (array/push res (get (get cols ci) i))))
   res)
 
 (defn distinct
@@ -1028,7 +1028,7 @@ value, one key will be ignored."
   [xs]
   (def ret @[])
   (def seen @{})
-  (loop [x :in xs] (if seen.x nil (do (set seen.x true) (array/push ret x))))
+  (loop [x :in xs] (if (get seen x) nil (do (put seen x true) (array/push ret x))))
   ret)
 
 (defn flatten-into
@@ -1052,7 +1052,7 @@ value, one key will be ignored."
   like @[k v k v ...]. Returns a new array."
   [dict]
   (def ret (array/new (* 2 (length dict))))
-  (loop [k :keys dict] (array/push ret k dict.k))
+  (loop [k :keys dict] (array/push ret k (get dict k)))
   ret)
 
 (defn interpose
@@ -1064,7 +1064,7 @@ value, one key will be ignored."
   (if (> len 0) (put ret 0 (get ind 0)))
   (var i 1)
   (while (< i len)
-    (array/push ret sep ind.i)
+    (array/push ret sep (get ind i))
     (++ i))
   ret)
 
@@ -1105,7 +1105,7 @@ value, one key will be ignored."
                (++ i)
                (if (= i len)
                  (onmatch)
-                 (match-1 pattern.i (tuple get $arr i) aux seen))))
+                 (match-1 (get pattern i) (tuple get $arr i) aux seen))))
            ,sentinel)))
 
     (dictionary? pattern)
@@ -1142,7 +1142,7 @@ value, one key will be ignored."
           (= i len-1) (get cases i)
           (< i len-1) (do
                         (def $res (gensym))
-                        ~(if (= ,sentinel (def ,$res ,(match-1 cases.i $x (fn [] (get cases (inc i))) @{})))
+                        ~(if (= ,sentinel (def ,$res ,(match-1 (get cases i) $x (fn [] (get cases (inc i))) @{})))
                            ,(aux (+ 2 i))
                            ,$res)))) 0)))
 
@@ -1200,19 +1200,19 @@ value, one key will be ignored."
 (defn doc*
   "Get the documentation for a symbol in a given environment."
   [env sym]
-  (def x env.sym)
+  (def x (get env sym))
   (if (not x)
     (print "symbol " sym " not found.")
     (do
       (def bind-type
         (string "    "
                 (cond
-                  x:ref (string :var " (" (type (get x:ref 0)) ")")
-                  x:macro :macro
-                  (type x:value))
+                  (x :ref) (string :var " (" (type (get (x :ref) 0)) ")")
+                  (x :macro) :macro
+                  (type (x :value)))
                 "\n"))
-      (def sm x:source-map)
-      (def d x:doc)
+      (def sm (x :source-map))
+      (def d (x :doc))
       (print "\n\n"
              (if d bind-type "")
              (if-let [[path start end] sm] (string "    " path " (" start ":" end ")\n") "")
@@ -1239,7 +1239,7 @@ value, one key will be ignored."
     (def newt @{})
     (var key (next t nil))
     (while (not= nil key)
-      (put newt (macex1 key) (on-value t.key))
+      (put newt (macex1 key) (on-value (get t key)))
       (set key (next t key)))
     newt)
 
@@ -1301,10 +1301,10 @@ value, one key will be ignored."
 
   (defn dotup [t]
     (def h (get t 0))
-    (def s specs.h)
-    (def entry (or *env*.h {}))
-    (def m entry:value)
-    (def m? entry:macro)
+    (def s (get specs h))
+    (def entry (or (get *env* h) {}))
+    (def m (entry :value))
+    (def m? (entry :macro))
     (cond
       s (s t)
       m? (m ;(tuple/slice t 1))
@@ -1527,7 +1527,7 @@ value, one key will be ignored."
   (def res (compile form *env* "eval"))
   (if (= (type res) :function)
     (res)
-    (error res:error)))
+    (error (res :error))))
 
 (do
   (def syspath (or (os/getenv "JANET_PATH") "/usr/local/lib/janet/"))
@@ -1600,17 +1600,17 @@ value, one key will be ignored."
     (def cache @{})
     (def loading @{})
     (fn require [path & args]
-      (when loading.path
+      (when (get loading path)
         (error (string "circular dependency: module " path " is loading")))
       (def {:exit exit-on-error} (table ;args))
-      (if-let [check cache.path]
+      (if-let [check (get cache path)]
         check
         (if-let [f (find-mod path)]
           (do
             # Normal janet module
             (def newenv (make-env))
-            (set cache.path newenv)
-            (set loading.path true)
+            (put cache path newenv)
+            (put loading path true)
             (defn chunks [buf _] (file/read f 1024 buf))
             (run-context newenv chunks
                          (fn [sig x f source]
@@ -1619,7 +1619,7 @@ value, one key will be ignored."
                              (if exit-on-error (os/exit 1))))
                          path)
             (file/close f)
-            (set loading.path false)
+            (put loading path false)
             newenv)
           (do
             # Try native module
@@ -1637,7 +1637,7 @@ value, one key will be ignored."
         :prefix prefix} (table ;args))
   (def newenv (require path ;args))
   (def prefix (or (and as (string as "/")) prefix (string path "/")))
-  (loop [[k v] :pairs newenv :when (not v:private)]
+  (loop [[k v] :pairs newenv :when (not (v :private))]
     (def newv (table/setproto @{:private true} v))
     (put env (symbol prefix k) newv)))
 
@@ -1680,5 +1680,5 @@ value, one key will be ignored."
   (def symbol-set @{})
   (loop [envi :in envs
          k :keys envi]
-    (set symbol-set.k true))
+    (put symbol-set k true))
   (sort (keys symbol-set)))
diff --git a/src/core/multisym.c b/src/core/multisym.c
deleted file mode 100644
index 761e5b48..00000000
--- a/src/core/multisym.c
+++ /dev/null
@@ -1,107 +0,0 @@
-/*
-* Copyright (c) 2019 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
-* deal in the Software without restriction, including without limitation the
-* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
-* sell copies of the Software, and to permit persons to whom the Software is
-* furnished to do so, subject to the following conditions:
-*
-* The above copyright notice and this permission notice shall be included in
-* all copies or substantial portions of the Software.
-*
-* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
-* IN THE SOFTWARE.
-*/
-
-#include <janet/janet.h>
-#include "compile.h"
-#include "emit.h"
-#include "vector.h"
-
-/* Parse a part of a symbol that can be used for building up code. */
-static JanetSlot multisym_parse_part(JanetCompiler *c, const uint8_t *sympart, int32_t len) {
-    if (sympart[0] == ':') {
-        return janetc_cslot(janet_keywordv(sympart + 1, len - 1));
-    } else {
-        double index;
-        if (janet_scan_number(sympart + 1, len - 1, &index)) {
-            /* not a number */
-            return janetc_resolve(c, janet_symbol(sympart + 1, len - 1));
-        } else {
-            /* is a number */
-            return janetc_cslot(janet_wrap_number(index));
-        }
-    }
-}
-
-static JanetSlot multisym_do_parts(JanetFopts opts, int put, const uint8_t *sym, Janet rvalue) {
-    JanetSlot slot;
-    JanetFopts subopts = janetc_fopts_default(opts.compiler);
-    int i, j;
-    for (i = 1, j = 0; sym[i]; i++) {
-        if (sym[i] == ':' || sym[i] == '.') {
-            if (j) {
-                JanetSlot target = janetc_gettarget(subopts);
-                JanetSlot value = multisym_parse_part(opts.compiler, sym + j, i - j);
-                janetc_emit_sss(opts.compiler, JOP_GET, target, slot, value, 1);
-                slot = target;
-            } else {
-                const uint8_t *nextsym = janet_symbol(sym + j, i - j);
-                slot = janetc_resolve(opts.compiler, nextsym);
-            }
-            j = i;
-        }
-    }
-
-    if (j) {
-        /* multisym (outermost get or put) */
-        JanetSlot target = janetc_gettarget(opts);
-        JanetSlot key = multisym_parse_part(opts.compiler, sym + j, i - j);
-        if (put) {
-            subopts.flags = JANET_FOPTS_HINT;
-            subopts.hint = target;
-            JanetSlot r_slot = janetc_value(subopts, rvalue);
-            janetc_emit_sss(opts.compiler, JOP_PUT, slot, key, r_slot, 0);
-            janetc_copy(opts.compiler, target, r_slot);
-        } else {
-            janetc_emit_sss(opts.compiler, JOP_GET, target, slot, key, 1);
-        }
-        return target;
-    } else {
-        /* normal symbol */
-        if (put) {
-            JanetSlot ret, dest;
-            dest = janetc_resolve(opts.compiler, sym);
-            if (!(dest.flags & JANET_SLOT_MUTABLE)) {
-                janetc_cerror(opts.compiler, "cannot set constant");
-                return janetc_cslot(janet_wrap_nil());
-            }
-            subopts.flags = JANET_FOPTS_HINT;
-            subopts.hint = dest;
-            ret = janetc_value(subopts, rvalue);
-            janetc_copy(opts.compiler, dest, ret);
-            return ret;
-        }
-        return janetc_resolve(opts.compiler, sym);
-    }
-}
-
-/* Check if a symbol is a multisym, and if so, transform
- * it and emit the code for treating it as a bunch of nested
- * gets. */
-JanetSlot janetc_sym_rvalue(JanetFopts opts, const uint8_t *sym) {
-    return multisym_do_parts(opts, 0, sym, janet_wrap_nil());
-}
-
-/* Check if a symbol is a multisym, and if so, transform
- * it into the correct 'put' expression. */
-JanetSlot janetc_sym_lvalue(JanetFopts opts, const uint8_t *sym, Janet value) {
-    return multisym_do_parts(opts, 1, sym, value);
-}
diff --git a/src/core/specials.c b/src/core/specials.c
index 182e069b..db00e93f 100644
--- a/src/core/specials.c
+++ b/src/core/specials.c
@@ -182,19 +182,47 @@ static const Janet *janetc_make_sourcemap(JanetCompiler *c) {
 }
 
 static JanetSlot janetc_varset(JanetFopts opts, int32_t argn, const Janet *argv) {
-    /*JanetFopts subopts = janetc_fopts_default(opts.compiler);*/
-    /*JanetSlot ret, dest;*/
-    Janet head;
     if (argn != 2) {
         janetc_cerror(opts.compiler, "expected 2 arguments");
         return janetc_cslot(janet_wrap_nil());
     }
-    head = argv[0];
-    if (!janet_checktype(head, JANET_SYMBOL)) {
-        janetc_cerror(opts.compiler, "expected symbol");
+    JanetFopts subopts = janetc_fopts_default(opts.compiler);
+    if (janet_checktype(argv[0], JANET_SYMBOL)) {
+        /* Normal var - (set a 1) */
+        const uint8_t *sym = janet_unwrap_symbol(argv[0]);
+        JanetSlot dest = janetc_resolve(opts.compiler, sym);
+        if (!(dest.flags & JANET_SLOT_MUTABLE)) {
+            janetc_cerror(opts.compiler, "cannot set constant");
+            return janetc_cslot(janet_wrap_nil());
+        }
+        subopts.flags = JANET_FOPTS_HINT;
+        subopts.hint = dest;
+        JanetSlot ret = janetc_value(subopts, argv[1]);
+        janetc_copy(opts.compiler, dest, ret);
+        return ret;
+    } else if (janet_checktype(argv[0], JANET_TUPLE)) {
+        /* Set a field (setf behavior) - (set (tab :key) 2) */
+        const Janet *tup = janet_unwrap_tuple(argv[0]);
+        /* Tuple must have 2 elements */
+        if (janet_tuple_length(tup) != 2) {
+            janetc_cerror(opts.compiler, "expected 2 element tuple for l-value to set");
+            return janetc_cslot(janet_wrap_nil());
+        }
+        JanetSlot ds = janetc_value(subopts, tup[0]);
+        JanetSlot key = janetc_value(subopts, tup[1]);
+        /* Can't be tail position because we will emit a PUT instruction afterwards */
+        /* Also can't drop either */
+        opts.flags &= ~(JANET_FOPTS_TAIL | JANET_FOPTS_DROP);
+        JanetSlot rvalue = janetc_value(opts, argv[1]);
+        /* Emit the PUT instruction */
+        janetc_emit_sss(opts.compiler, JOP_PUT, ds, key, rvalue, 0);
+        return rvalue;
+    } else {
+        /* Error */
+        janet_inspect(argv[0]);
+        janetc_cerror(opts.compiler, "expected symbol or tuple for l-value to set");
         return janetc_cslot(janet_wrap_nil());
     }
-    return janetc_sym_lvalue(opts, janet_unwrap_symbol(head), argv[1]);
 }
 
 /* Add attributes to a global def or var table */
diff --git a/tools/cook.janet b/tools/cook.janet
index 2d86d360..727e3444 100644
--- a/tools/cook.janet
+++ b/tools/cook.janet
@@ -76,6 +76,20 @@
   [name]
   (string "build" sep name modext))
 
+(defn- make-define
+  "Generate strings for adding custom defines to the compiler."
+  [define value]
+  (def prefix (if is-win "\\D" "-D"))
+  (if value
+    (string prefix define "=" value)
+    (string prefix define)))
+
+(defn- make-defines
+  "Generate many defines. Takes a dictionary of defines. If a value is
+  true, generates -DNAME (\\DNAME on windows), otherwise -DNAME=value."
+  [defines]
+  (seq [[d v] :pairs defines] (make-define d (if (not= v true) v))))
+
 # Defaults
 (def OPTIMIZE 2)
 (def CC (if is-win "cl" "cc"))
@@ -85,18 +99,19 @@
 (defn- compile-c
   "Compile a C file into an object file."
   [opts src dest]
-  (def cc (or opts:compiler CC))
-  (def cflags (or opts:cflags CFLAGS))
+  (def cc (or (opts :compiler) CC))
+  (def cflags (or (opts :cflags) CFLAGS))
+  (def defines (interpose " " (make-defines (or (opts :defines) {}))))
   (if (older-than dest src)
     (if is-win
-      (shell cc " /nologo /c " cflags " /Fo" dest " " src)
-      (shell cc " " cflags " -o " dest " -c " src))))
+      (shell cc " " ;defines " /nologo /c " cflags " /Fo" dest " " src)
+      (shell cc " " ;defines " " cflags " -o " dest " -c " src))))
 
 (defn- link-c
   "Link a number of object files together."
   [opts target & objects]
-  (def ld (or opts:linker LD))
-  (def cflags (or opts:cflags CFLAGS))
+  (def ld (or (opts :linker) LD))
+  (def cflags (or (opts :cflags) CFLAGS))
   (def olist (string/join objects " "))
   (if (older-than-some target objects)
     (if is-win
@@ -129,17 +144,19 @@
   [& opts]
   (def opt-table (table ;opts))
   (mkdir "build")
-  (loop [src :in opt-table:source]
+  (def sources (opt-table :source))
+  (def name (opt-table :name))
+  (loop [src :in sources]
     (compile-c opt-table src (object-name src)))
-  (def objects (map object-name opt-table:source))
-  (when opt-table:embedded
-    (loop [src :in opt-table:embedded]
+  (def objects (map object-name sources))
+  (when-let [embedded (opt-table :embedded)]
+    (loop [src :in embedded]
       (def c-src (embed-c-name src))
       (def o-src (embed-o-name src))
       (array/push objects o-src)
       (create-buffer-c src c-src (embed-name src))
       (compile-c opt-table c-src o-src)))
-  (link-c opt-table (lib-name opt-table:name) ;objects))
+  (link-c opt-table (lib-name name) ;objects))
 
 (defn clean
   "Remove all built artifacts."
diff --git a/tools/gendoc.janet b/tools/gendoc.janet
index 7f175daf..490a01f4 100644
--- a/tools/gendoc.janet
+++ b/tools/gendoc.janet
@@ -44,7 +44,7 @@
   "Trim leading newlines"
   [str]
   (var i 0)
-  (while (= 10 str.i) (++ i))
+  (while (= 10 (get str i)) (++ i))
   (string/slice str i))
 
 (defn- html-escape
@@ -52,7 +52,7 @@
   [str]
   (def buf @"")
   (loop [byte :in str]
-    (if-let [rep escapes.byte]
+    (if-let [rep (get escapes byte)]
       (buffer/push-string buf rep)
       (buffer/push-byte buf byte)))
   buf)
@@ -90,7 +90,7 @@
 # Generate parts and print them to stdout
 (def parts (seq [[k entry]
                  :in (sort (pairs (table/getproto _env)))
-                 :when (and entry:doc (not entry:private))]
+                 :when (and (get entry :doc) (not (get entry :private)))]
                 (emit-item k entry)))
 (print
   prelude
diff --git a/tools/marshal_core.janet b/tools/marshal_core.janet
index 2c856219..21534e1f 100644
--- a/tools/marshal_core.janet
+++ b/tools/marshal_core.janet
@@ -1,12 +1,10 @@
-#
 # Tool to dump a marshalled version of the janet core to stdout. The
 # image should eventually allow janet to be started from a pre-compiled
 # image rather than recompiled every time from the embedded source. More
 # work will go into shrinking the image (it isn't currently that large but
 # could be smaller), creating the mechanism to load the image, and modifying
-# the build process to compile janet with a build int image rather than
+# the build process to compile janet with a built image rather than
 # embedded source.
-#
 
 # Get image. This image contains as much of the core library and documentation that
 # can be written to an image (no cfunctions, no abstracts (stdout, stdin, stderr)),
diff --git a/tools/tmcorelib.janet b/tools/tmcorelib.janet
index 69f05291..a9df827d 100644
--- a/tools/tmcorelib.janet
+++ b/tools/tmcorelib.janet
@@ -1,4 +1,5 @@
 # Helper to generate core library mappings for janet
+# Used to help build the tmLanguage grammar.
 
 (def allsyms (all-symbols))
 
@@ -22,7 +23,7 @@
   [str]
   (def buf @"")
   (loop [byte :in str]
-    (if-let [rep escapes.byte]
+    (if-let [rep (get escapes byte)]
       (buffer/push-string buf rep)
       (buffer/push-byte buf byte)))
   buf)