diff --git a/build/post-compile.js b/build/post-compile.js
index ebd80869d..6ea6cda9f 100644
--- a/build/post-compile.js
+++ b/build/post-compile.js
@@ -40,7 +40,7 @@
     // flip `typeof` expressions to help optimize Safari and
     // correct the AMD module definition for AMD build optimizers
     // (e.g. from `"number" == typeof x` to `typeof x == "number")
-    source = source.replace(/(return)?\s*("[^"]+")\s*([!=]=)\s*(typeof(?:\s*\([^)]+\)|\s+[\w.]+))/g, function(match, ret, type, equality, expression) {
+    source = source.replace(/(return)?("[^"]+")\s*([!=]=)\s*(typeof(?:\s*\([^)]+\)|\s+[\w.]+))/g, function(match, ret, type, equality, expression) {
       return (ret ? ret + ' ' : '') + expression + equality + type;
     });