diff --git a/lib/ace/narcissus/jslex.js b/lib/ace/narcissus/jslex.js
index c551792f..e2c5a646 100644
--- a/lib/ace/narcissus/jslex.js
+++ b/lib/ace/narcissus/jslex.js
@@ -281,6 +281,8 @@ Tokenizer.prototype = {
 
         var hasEscapes = false;
         var delim = ch;
+        if (input.length <= this.cursor)
+            throw this.newSyntaxError("Unterminated string literal");
         while ((ch = input[this.cursor++]) !== delim) {
             if (this.cursor == input.length)
                 throw this.newSyntaxError("Unterminated string literal");