diff --git a/min/builder/bm.js b/min/builder/bm.js
index ec06831..56a639f 100644
--- a/min/builder/bm.js
+++ b/min/builder/bm.js
@@ -1,22 +1,23 @@
 javascript:(function() {
-    function add(uri) {
-        (0 === uri.indexOf(home))
-        && (!/[\?&]/.test(uri))
-        && uris.push(escape(uri.substr(home.length)));
-    }
-    function sheet(ss) {
-        ss.href && add(ss.href);
-        if (ss.cssRules) {
-            var i = 0, r;
-            while (r = ss.cssRules[i++])
-                r.styleSheet && sheet(r.styleSheet);
-        }
-    }    
     var d = document
        ,uris = []
        ,i = 0
        ,o
        ,home = (location + '').split('/').splice(0, 3).join('/') + '/';
+    function add(uri) {
+        return (0 === uri.indexOf(home))
+            && (!/[\?&]/.test(uri))
+            && uris.push(escape(uri.substr(home.length)));
+    };
+    function sheet(ss) {
+        // we must check the domain with add() before accessing ss.cssRules
+        // otherwise a security exception will be thrown
+        if (ss.href && add(ss.href) && ss.cssRules) {
+            var i = 0, r;
+            while (r = ss.cssRules[i++])
+                r.styleSheet && sheet(r.styleSheet);
+        }
+    };
     while (o = d.getElementsByTagName('script')[i++])
         o.src && !(o.type && /vbs/i.test(o.type)) && add(o.src);
     i = 0;
@@ -25,5 +26,7 @@ javascript:(function() {
     if (uris.length)
         window.open('%BUILDER_URL%#' + uris.join(','));
     else
-        alert('No minifiable resources found.');
+        alert('No js/css files found with URLs within "' 
+            + home.split('/')[2]
+            + '".\n(This tool is limited to URLs with the same domain.)');
 })();
\ No newline at end of file