diff --git a/showup.js b/showup.js
index 39b7fde..16516ad 100644
--- a/showup.js
+++ b/showup.js
@@ -111,7 +111,9 @@
    * @return-{boolean}
    */
   var hasClass = function (className) {
-    return this.className.indexOf(className) > -1;
+    var regex = new RegExp('(^| )' + className + '($| )');
+    
+    return regex.test(this.className);
   };