diff --git a/lib/6to5/types.js b/lib/6to5/types.js
index f6eee9a4da..f303e3cb02 100644
--- a/lib/6to5/types.js
+++ b/lib/6to5/types.js
@@ -166,6 +166,10 @@ exports.needsParans = function (node, parent) {
   }
 
   if (node.type === "FunctionExpression") {
+    if (parent.type === "ExpressionStatement") {
+      return true;
+    }
+
     if (parent.type === "MemberExpression" && parent.object === node) {
       return true;
     }