diff --git a/js/anchor.js b/js/anchor.js
index 1860e8c..7c8905d 100644
--- a/js/anchor.js
+++ b/js/anchor.js
@@ -230,7 +230,7 @@ function getSubclass( Super ) {
     Item.optionKeys = Super.optionKeys.slice( 0 );
     // add defaults keys to optionKeys, dedupe
     Object.keys( Item.defaults ).forEach( function( key ) {
-      if ( !Item.optionKeys.indexOf( key ) != 1 ) {
+      if ( Item.optionKeys.indexOf( key ) === -1 ) {
         Item.optionKeys.push( key );
       }
     } );