diff --git a/app/assets/javascripts/maps.js.coffee b/app/assets/javascripts/maps.js.coffee
index 4c2fab22..ebcdca25 100644
--- a/app/assets/javascripts/maps.js.coffee
+++ b/app/assets/javascripts/maps.js.coffee
@@ -37,7 +37,7 @@ $(document).ready ->
     ).addTo map
 
     url = $(this).data 'url'
-    if location.search && url.indexOf '?'
+    if location.search && url.indexOf('?') >= 0
       url += '&' + location.search.substr 1
     else
       url += location.search