diff --git a/lib/babel/transformation/transformers/es6/classes.js b/lib/babel/transformation/transformers/es6/classes.js
index 6d1705bffa..20df75660c 100644
--- a/lib/babel/transformation/transformers/es6/classes.js
+++ b/lib/babel/transformation/transformers/es6/classes.js
@@ -83,7 +83,14 @@ ClassTransformer.prototype.run = function () {
     constructor = t.functionDeclaration(className, [], constructorBody);
     body.push(constructor);
   } else {
-    constructor = t.functionExpression(null, [], constructorBody);
+    var constructorName = null;
+    // when there is only constructor or nothing, constructor is not
+    // wrapped in closure and has to be named
+    if (this.node.body.body.length <= 1) {
+      constructorName = className;
+    }
+
+    constructor = t.functionExpression(constructorName, [], constructorBody);
     body.push(t.variableDeclaration("var", [
       t.variableDeclarator(className, constructor)
     ]));