diff --git a/src/compiler/transformer.ts b/src/compiler/transformer.ts
index 53a07872621..a18b8546db8 100644
--- a/src/compiler/transformer.ts
+++ b/src/compiler/transformer.ts
@@ -210,7 +210,12 @@ namespace ts {
          * Sets flags that control emit behavior of a node.
          */
         function setNodeEmitFlags<T extends Node>(node: T, flags: NodeEmitFlags) {
-            getEmitOptions(node, /*create*/ true).flags = flags;
+            const options = getEmitOptions(node, /*create*/ true);
+            if (flags & NodeEmitFlags.Merge) {
+                flags = options.flags | (flags & ~NodeEmitFlags.Merge);
+            }
+
+            options.flags = flags;
             return node;
         }
 
diff --git a/src/compiler/transformers/es6.ts b/src/compiler/transformers/es6.ts
index 4c4e65e7910..ef9f4f29d1d 100644
--- a/src/compiler/transformers/es6.ts
+++ b/src/compiler/transformers/es6.ts
@@ -959,7 +959,7 @@ namespace ts {
                         createStatement(
                             createAssignment(
                                 setNodeEmitFlags(getMutableClone(name), NodeEmitFlags.NoSourceMap),
-                                setNodeEmitFlags(visitNode(initializer, visitor, isExpression), NodeEmitFlags.NoSourceMap),
+                                setNodeEmitFlags(visitNode(initializer, visitor, isExpression), NodeEmitFlags.NoSourceMap | NodeEmitFlags.Merge),
                                 /*location*/ parameter
                             )
                         )