diff --git a/common/modules/io.jsm b/common/modules/io.jsm
index c807fdf0..030d9b57 100644
--- a/common/modules/io.jsm
+++ b/common/modules/io.jsm
@@ -489,7 +489,7 @@ var IO = Module("io", {
      *     otherwise, the return value of *func*.
      */
     withTempFiles: function (func, self, checked) {
-        let args = array(util.range(0, func.length)).map(this.createTempFile).array;
+        let args = array(util.range(0, func.length)).map(this.closure.createTempFile).array;
         try {
             if (!args.every(util.identity))
                 return false;