diff --git a/contentscript.js b/contentscript.js
index 78db557..c98932a 100644
--- a/contentscript.js
+++ b/contentscript.js
@@ -81,6 +81,10 @@
 }
 
 function fetchRdf(rdfUrl, failfunc) {
+  // avoid mixed content errors
+  if (rdfUrl.startsWith('http:')) {
+    rdfUrl = rdfUrl.substring(5);
+  }
   var onFail = $.noop;
   if (typeof failFunc == 'function') {
     onFail = failFunc;