diff --git a/wolf.js b/wolf.js
index 719b17b..20308eb 100755
--- a/wolf.js
+++ b/wolf.js
@@ -139,7 +139,13 @@
                 return;
             url = new URL(url, document.baseURI).href;
             var obj = objs[url];
-            if (!obj) {
+            var cbl = obj instanceof CallbackList ? obj : null;
+            //console.debug("require: " + url + " " + (cbl ? "(precache)" : obj ? "(cache)" : "(fetch)"));
+            if (cbl) {
+                cbl.add(callback);
+            } else if (!obj) {
+                cbl = objs[url] = new CallbackList();
+                cbl.add(callback);
                 TOOLS.wGet(url, function (data) {
                     try {
                         var inc = Function("'use strict';return " + data + ";\n//# sourceURL=" + url);
@@ -149,7 +155,7 @@
                     }
                     instantiate(inc(), function (lobj) {
                         objs[url] = lobj;
-                        callback && callback(lobj);
+                        cbl.fire([lobj]);
                     }, url);
                 }, function (error, stage) {
                     if (error && error.status && error.status == 404)