diff --git a/dev/js/src/api.js b/dev/js/src/api.js
index 00821de..d6493cb 100644
--- a/dev/js/src/api.js
+++ b/dev/js/src/api.js
@@ -6,7 +6,7 @@
   // http://www.javascriptkit.com/javatutors/loadjavascriptcss.shtml
   // http://stackoverflow.com/questions/6112744/load-javascript-on-demand
 
-  KorAP.URL = KorAP.URL || 'http://korap.ids-mannheim.de/kalamar';
+  KorAP.URL = KorAP.URL !== undefined ? KorAP.URL : 'http://korap.ids-mannheim.de/kalamar';
 
   KorAP.API = KorAP.API || {};