diff --git a/lib/$.coffee b/lib/$.coffee
index 0c7814c21..cb3c56bad 100644
--- a/lib/$.coffee
+++ b/lib/$.coffee
@@ -16,7 +16,7 @@ $.extend $,
   MINUTE: 1000 * 60
   HOUR  : 1000 * 60 * 60
   DAY   : 1000 * 60 * 60 * 24
-  engine: <% if (type === 'crx') { %>webkit<% } else if (type === 'userjs') { %>presto<% } else { %>gecko<% } %>
+  engine: '<% if (type === 'crx') { %>webkit<% } else if (type === 'userjs') { %>presto<% } else { %>gecko<% } %>'
   id: (id) ->
     d.getElementById id
   ready: (fc) ->