--- a/browser/base/content/test/performance/browser_startup.js
+++ b/browser/base/content/test/performance/browser_startup.js
@@ -114,16 +114,17 @@ const startupPhases = {
   "before becoming idle": {blacklist: {
     components: new Set([
       "UnifiedComplete.js",
     ]),
     modules: new Set([
       "resource://gre/modules/AsyncPrefs.jsm",
       "resource://gre/modules/LoginManagerContextMenu.jsm",
       "resource://gre/modules/Task.jsm",
+      "resource://pdf.js/PdfStreamConverter.jsm",
     ]),
   }},
 };
 
 if (Services.prefs.getBoolPref("browser.startup.blankWindow")) {
   startupPhases["before profile selection"].whitelist.components.add("XULStore.js");
 }
 

--- a/browser/base/content/test/performance/browser_startup_content.js
+++ b/browser/base/content/test/performance/browser_startup_content.js
@@ -24,16 +24,18 @@ const blacklist = {
   ]),
   modules: new Set([
     "resource:///modules/ContentWebRTC.jsm",
     "resource://gre/modules/InlineSpellChecker.jsm",
     "resource://gre/modules/InlineSpellCheckerContent.jsm",
     "resource://gre/modules/Promise.jsm",
     "resource://gre/modules/Task.jsm",
     "resource://gre/modules/osfile.jsm",
+    "resource://pdf.js/PdfJs.jsm",
+    "resource://pdf.js/PdfStreamConverter.jsm",
   ]),
   services: new Set([
     "@mozilla.org/base/telemetry-startup;1",
     "@mozilla.org/push/Service;1",
   ])
 };
 
 add_task(async function() {

--- a/browser/extensions/pdfjs/content/PdfJsRegistration.jsm
+++ b/browser/extensions/pdfjs/content/PdfJsRegistration.jsm
@@ -16,32 +16,41 @@
 "use strict";
 
 var EXPORTED_SYMBOLS = ["PdfJsRegistration"];
 
 const Cm = Components.manager;
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
+ChromeUtils.defineModuleGetter(this, "PdfStreamConverter",
+  "resource://pdf.js/PdfStreamConverter.jsm");
 
 // Register/unregister a constructor as a factory.
 function StreamConverterFactory() {}
 StreamConverterFactory.prototype = {
 
   // properties required for XPCOM registration:
   _classID: Components.ID("{d0c5195d-e798-49d4-b1d3-9324328b2291}"),
   _classDescription: "pdf.js Component",
   _contractID: "@mozilla.org/streamconv;1?from=application/pdf&to=*/*",
 
   _classID2: Components.ID("{d0c5195d-e798-49d4-b1d3-9324328b2292}"),
   _contractID2: "@mozilla.org/streamconv;1?from=application/pdf&to=text/html",
 
   register: function register() {
-    ChromeUtils.import("resource://pdf.js/PdfStreamConverter.jsm");
-    var factory = XPCOMUtils._getFactory(PdfStreamConverter);
+    var factory = {
+      createInstance(outer, iid) {
+        if (outer)
+          throw Cr.NS_ERROR_NO_AGGREGATION;
+        return (new PdfStreamConverter()).QueryInterface(iid);
+      },
+      QueryInterface: ChromeUtils.generateQI([Ci.nsIFactory])
+    };
+
     this._factory = factory;
 
     var registrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
     registrar.registerFactory(this._classID, this._classDescription,
                               this._contractID, factory);
     registrar.registerFactory(this._classID2, this._classDescription,
                               this._contractID2, factory);
   },