diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index 801b3687d5..d44d6c6f25 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -162,17 +162,22 @@ Class.prototype.buildBody = function () {
 Class.prototype.pushMethod = function (node) {
   var methodName = node.key;
 
-  var mutatorMap = this.instanceMutatorMap;
-  if (node.static) mutatorMap = this.staticMutatorMap;
-
   var kind = node.kind;
 
   if (kind === "") {
-    kind = "value";
-    util.pushMutatorMap(mutatorMap, methodName, "writable", t.identifier("true"));
-  }
+    // method
 
-  util.pushMutatorMap(mutatorMap, methodName, kind, node);
+    var className = this.className;
+    if (!node.static) className = t.memberExpression(className, t.identifier("prototype"));
+    methodName = t.memberExpression(className, methodName, node.computed);
+
+    this.body.push(t.expressionStatement(t.assignmentExpression("=", methodName, node.value)));
+  } else {
+    // mutator
+    var mutatorMap = this.instanceMutatorMap;
+    if (node.static) mutatorMap = this.staticMutatorMap;
+    util.pushMutatorMap(mutatorMap, methodName, kind, node);
+  }
 };
 
 /**