diff --git a/lib/MemberBuilder.js b/lib/MemberBuilder.js
index ac8dae1..547606b 100644
--- a/lib/MemberBuilder.js
+++ b/lib/MemberBuilder.js
@@ -224,7 +224,7 @@ exports._validateMethod = function(
         }
 
         // do not allow overriding concrete methods with abstract
-        if ( keywords[ 'abstract' ] && !( util.isAbstractMethod( prev ) ) )
+        if ( keywords[ 'abstract' ] && !( prev_keywords[ 'abstract' ] ) )
         {
             throw TypeError(
                 "Cannot override concrete method '" + name + "' with " +