--- a/devtools/shared/Loader.jsm
+++ b/devtools/shared/Loader.jsm
@@ -177,19 +177,22 @@ DevToolsLoader.prototype = {
     // can't be flagged as invisible to debugger.
     if (this.invisibleToDebugger) {
       delete modules.promise;
     }
 
     // Register custom pseudo modules to the current loader instance
     let loader = this._provider.loader;
     for (let id in modules) {
-      let exports = modules[id];
       let uri = resolveURI(id, loader.mapping);
-      loader.modules[uri] = { exports };
+      loader.modules[uri] = {
+        get exports() {
+          return modules[id];
+        }
+      };
     }
 
     // Register custom globals to the current loader instance
     globals.loader.id = this.id;
     Object.defineProperties(loader.globals, descriptor(globals));
 
     // Expose lazy helpers on loader
     this.lazyGetter = globals.loader.lazyGetter;