diff --git a/lib/less/tree/ruleset.js b/lib/less/tree/ruleset.js
index 9b94844..571376f 100644
--- a/lib/less/tree/ruleset.js
+++ b/lib/less/tree/ruleset.js
@@ -40,7 +40,7 @@ tree.Ruleset.prototype = {
         if (this._rulesets) { return this._rulesets }
         else {
             return this._rulesets = this.rules.filter(function (r) {
-                if (r instanceof tree.Ruleset || r instanceof tree.mixin.Definition) { return r }
+                return (r instanceof tree.Ruleset) || (r instanceof tree.mixin.Definition);
             });
         }
     },