diff --git a/lib/client/polyfill.js b/lib/client/polyfill.js
index f6a14af7..a66eb22e 100644
--- a/lib/client/polyfill.js
+++ b/lib/client/polyfill.js
@@ -105,7 +105,6 @@ var Util, DOM, jQuery;
         };
     }
     
-    DOM.scrollByPages           = Util.retFalse;
     /* function polyfill webkit standart function
      *    https://gist.github.com/2581101
      */
diff --git a/lib/server/readify.js b/lib/server/readify.js
index 4e78e8cd..884d5351 100644
--- a/lib/server/readify.js
+++ b/lib/server/readify.js
@@ -54,7 +54,7 @@
             callback(null, data || {
                 'mode'          : 0,
                 'size'          : 0,
-                'isDirectory'   : Util.retFalse
+                'isDirectory'   : function() {}
             });
         });
     }
diff --git a/lib/util.js b/lib/util.js
index 37fb0743..e599d123 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -454,14 +454,6 @@
             
             return type;
         }
-        /**
-         * function return false
-         */
-        this.retFalse               = function() {
-            var ret = false;
-            
-            return ret;
-        };
         
         /**
          * function makes new array based on first