diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c7f7ef26b..247ff77e52 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.14.1
+
+ * Fix let scoping unneccesary override.
+
 # 1.14.6
 
  * Avoid ensuring a block on non-array node replacements.
diff --git a/lib/6to5/traverse/scope.js b/lib/6to5/traverse/scope.js
index 9666edafa3..98cf4f1710 100644
--- a/lib/6to5/traverse/scope.js
+++ b/lib/6to5/traverse/scope.js
@@ -23,7 +23,7 @@ function Scope(block, parent) {
 
 Scope.add = function (node, references) {
   if (!node) return;
-  _.merge(references, t.getIds(node, true));
+  _.defaults(references, t.getIds(node, true));
 };
 
 Scope.prototype.getReferences = function () {
diff --git a/lib/6to5/types/index.js b/lib/6to5/types/index.js
index 931cfa0ebb..f741debaff 100644
--- a/lib/6to5/types/index.js
+++ b/lib/6to5/types/index.js
@@ -162,7 +162,7 @@ t.toIdentifier = function (name) {
     return c ? c.toUpperCase() : "";
   });
 
-  return name;
+  return name || '_';
 };
 
 t.isValidIdentifier = function (name) {