diff --git a/acorn.js b/acorn.js
index 0f04af0ab9..0c01b6aae9 100644
--- a/acorn.js
+++ b/acorn.js
@@ -14,7 +14,7 @@
 // [ghbt]: https://github.com/marijnh/acorn/issues
 
 (function(exports) {
-  "strict mode";
+  "use strict";
 
   exports.version = "0.0.1";