diff --git a/lib/scope.js b/lib/scope.js
index 39bd9cbf..7b8d38a0 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -575,6 +575,8 @@ AST_Toplevel.DEFMETHOD("compute_char_frequency", function(options){
             base54.consider("catch");
         else if (node instanceof AST_Finally)
             base54.consider("finally");
+        else if (node instanceof AST_Yield)
+            base54.consider("yield");
         else if (node instanceof AST_Symbol && node.unmangleable(options))
             base54.consider(node.name);
         else if (node instanceof AST_Unary || node instanceof AST_Binary)