diff --git a/codemirror/addon/lint/css-lint.js b/codemirror/addon/lint/css-lint.js
index dac31f93..c5c8bb3d 100644
--- a/codemirror/addon/lint/css-lint.js
+++ b/codemirror/addon/lint/css-lint.js
@@ -19,14 +19,16 @@ CodeMirror.registerHelper("lint", "css", function(text) {
   var found = [];
   if (!window.CSSLint) return found;
 
+  // STYLISH: hack start
   var rules = CSSLint.getRules();
-  var allowedRules = ["display-property-grouping", "empty-rules", "errors", "known-properties"];
+  var allowedRules = ["display-property-grouping", "duplicate-properties", "empty-rules", "errors", "known-properties"];
   CSSLint.clearRules();
   rules.forEach(function(rule) {
     if (allowedRules.indexOf(rule.id) >= 0) {
       CSSLint.addRule(rule);
     }
   });
+  // STYLISH: hack end
 
   var results = CSSLint.verify(text), messages = results.messages, message = null;
   for ( var i = 0; i < messages.length; i++) {