diff --git a/lib/6to5/transformation/transformers/es6-default-parameters.js b/lib/6to5/transformation/transformers/es6-default-parameters.js
index 408c1a7e63..af1b163e5b 100644
--- a/lib/6to5/transformation/transformers/es6-default-parameters.js
+++ b/lib/6to5/transformation/transformers/es6-default-parameters.js
@@ -17,7 +17,7 @@ exports.Function = function (node, parent, scope, context, file) {
 
   var checkTDZ = function (ids) {
     var check = function (node, parent) {
-      if (!t.isIdentifier(node) || !t.isReferenced(node, parent)) return;
+      if (!t.isReferencedIdentifier(node, parent)) return;
 
       if (ids.indexOf(node.name) >= 0) {
         throw file.errorWithNode(node, "Temporal dead zone - accessing a variable before it's initialized");
diff --git a/lib/6to5/transformation/transformers/es6-let-scoping.js b/lib/6to5/transformation/transformers/es6-let-scoping.js
index b7d7f5fbb2..4d0f13910e 100644
--- a/lib/6to5/transformation/transformers/es6-let-scoping.js
+++ b/lib/6to5/transformation/transformers/es6-let-scoping.js
@@ -146,8 +146,7 @@ LetScoping.prototype.remap = function () {
   //
 
   var replace = function (node, parent, scope, context, remaps) {
-    if (!t.isIdentifier(node)) return;
-    if (!t.isReferenced(node, parent)) return;
+    if (!t.isReferencedIdentifier(node, parent)) return;
 
     var remap = remaps[node.name];
     if (!remap) return;
@@ -266,11 +265,8 @@ LetScoping.prototype.getLetReferences = function () {
       if (t.isFunction(node)) {
         traverse(node, {
           enter: function (node, parent) {
-            // not an identifier so we have no use
-            if (!t.isIdentifier(node)) return;
-
             // not a direct reference
-            if (!t.isReferenced(node, parent)) return;
+            if (!t.isReferencedIdentifier(node, parent)) return;
 
             // this scope has a variable with the same name so it couldn't belong
             // to our let scope
diff --git a/lib/6to5/transformation/transformers/optional-block-scoping-tdz.js b/lib/6to5/transformation/transformers/optional-block-scoping-tdz.js
index 972cca4567..27472f8bdf 100644
--- a/lib/6to5/transformation/transformers/optional-block-scoping-tdz.js
+++ b/lib/6to5/transformation/transformers/optional-block-scoping-tdz.js
@@ -16,8 +16,7 @@ exports.BlockStatement = function (node, parent, scope, context, file) {
 
   traverse(node, {
     enter: function (node, parent, scope, context, state) {
-      if (!t.isIdentifier(node)) return;
-      if (!t.isReferenced(node, parent)) return;
+      if (!t.isReferencedIdentifier(node, parent)) return;
 
       var declared = state.letRefs[node.name];
       if (!declared) return;
diff --git a/lib/6to5/transformation/transformers/optional-core-aliasing.js b/lib/6to5/transformation/transformers/optional-core-aliasing.js
index c0db8bd9bd..90bb4621a7 100644
--- a/lib/6to5/transformation/transformers/optional-core-aliasing.js
+++ b/lib/6to5/transformation/transformers/optional-core-aliasing.js
@@ -42,7 +42,7 @@ exports.ast = {
             context.skip();
             return t.prependToMemberExpression(node, file._coreId);
           }
-        } else if (t.isIdentifier(node) && !t.isMemberExpression(parent) && t.isReferenced(node, parent) && _.contains(ALIASABLE_CONSTRUCTORS, node.name)) {
+        } else if (t.isReferencedIdentifier(node, parent) && !t.isMemberExpression(parent) && _.contains(ALIASABLE_CONSTRUCTORS, node.name)) {
           // Symbol() -> _core.Symbol(); new Promise -> new _core.Promise
           return t.memberExpression(file._coreId, node);
         } else if (t.isCallExpression(node)) {
diff --git a/lib/6to5/types/index.js b/lib/6to5/types/index.js
index 31c783dc1f..8bc6cb5d75 100644
--- a/lib/6to5/types/index.js
+++ b/lib/6to5/types/index.js
@@ -263,6 +263,18 @@ t.isReferenced = function (node, parent) {
   return false;
 };
 
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Object} parent
+ * @returns {Boolean}
+ */
+
+t.isReferencedIdentifier = function (node, parent) {
+  return t.isIdentifier(node) && t.isReferenced(node, parent);
+};
+
 /**
  * Description
  *