diff --git a/js/phetmarks.js b/js/phetmarks.js
index c12db81..b212b39 100644
--- a/js/phetmarks.js
+++ b/js/phetmarks.js
@@ -275,7 +275,7 @@
           }, {
             value: 'testSims=' + accessibleSims.join( ',' ),
             text: 'Test only A11y sims',
-            default: false
+            default: true
           } ]
         } );
         modes.push( {