diff --git a/lib/ace/mode/eiffel.js b/lib/ace/mode/eiffel.js
index 2ef84ff8..f8ba173b 100644
--- a/lib/ace/mode/eiffel.js
+++ b/lib/ace/mode/eiffel.js
@@ -42,6 +42,7 @@ var Mode = function() {
 oop.inherits(Mode, TextMode);
 
 (function() {
+    this.lineCommentStart = "--";
     this.$id = "ace/mode/eiffel";
 }).call(Mode.prototype);