diff --git a/dom/media/IdpSandbox.jsm b/dom/media/IdpSandbox.jsm
index 61069223bc1e..96b12eeebab2 100644
--- a/dom/media/IdpSandbox.jsm
+++ b/dom/media/IdpSandbox.jsm
@@ -113,14 +113,14 @@ function createLocationFromURI(uri) {
  *
  * @param domain (string) the domain of the IdP
  * @param protocol (string?) the protocol of the IdP [default: 'default']
- * @param doc (obj) the current document
+ * @param win (obj) the current window
  * @throws if the domain or protocol aren't valid
  */
-function IdpSandbox(domain, protocol, doc) {
+function IdpSandbox(domain, protocol, win) {
   this.source = IdpSandbox.createIdpUri(domain, protocol || "default");
   this.active = null;
   this.sandbox = null;
-  this.document = doc;
+  this.window = win;
 }
 
 IdpSandbox.checkDomain = function(domain) {
@@ -181,7 +181,7 @@ IdpSandbox.prototype = {
 
   start: function() {
     if (!this.active) {
-      this.active = ResourceLoader.load(this.source, this.document)
+      this.active = ResourceLoader.load(this.source, this.window.document)
         .then(result => this._createSandbox(result));
     }
     return this.active;
@@ -222,19 +222,12 @@ IdpSandbox.prototype = {
       Cu.evalInSandbox(result.data, this.sandbox,
                        'latest', result.request.URI.spec, 1);
     } catch (e) {
+      // These can be passed straight on, because they are explicitly labelled
+      // as being IdP errors by the IdP and we drop line numbers as a result.
       if (e.name === 'IdpError' || e.name === 'IdpLoginError') {
         throw e;
       }
-      // Capture all the details from the error and log them to the console.
-      // This can't rethrow anything else because that could leak information
-      // about the internal workings of the IdP across origins.
-      let scriptErrorClass = Cc["@mozilla.org/scripterror;1"];
-      let scriptError = scriptErrorClass.createInstance(Ci.nsIScriptError);
-      scriptError.init(e.message, e.fileName, null, e.lineNumber, e.columnNumber,
-                       Ci.nsIScriptError.errorFlag, "content javascript");
-      let consoleService = Cc['@mozilla.org/consoleservice;1']
-          .getService(Ci.nsIConsoleService);
-      consoleService.logMessage(scriptError);
+      this._logError(e);
       throw new Error('Error in IdP, check console for details');
     }
 
@@ -244,6 +237,23 @@ IdpSandbox.prototype = {
     return registrar;
   },
 
+  // Capture all the details from the error and log them to the console.  This
+  // can't rethrow anything else because that could leak information about the
+  // internal workings of the IdP across origins.
+  _logError: function(e) {
+    let winID = this.window.QueryInterface(Ci.nsIInterfaceRequestor)
+        .getInterface(Ci.nsIDOMWindowUtils).currentInnerWindowID;
+    let scriptError = Cc["@mozilla.org/scripterror;1"]
+        .createInstance(Ci.nsIScriptError);
+    scriptError.initWithWindowID(e.message, e.fileName, null,
+                                 e.lineNumber, e.columnNumber,
+                                 Ci.nsIScriptError.errorFlag,
+                                 "content javascript", winID);
+    let consoleService = Cc['@mozilla.org/consoleservice;1']
+        .getService(Ci.nsIConsoleService);
+    consoleService.logMessage(scriptError);
+  },
+
   stop: function() {
     if (this.sandbox) {
       Cu.nukeSandbox(this.sandbox);
diff --git a/dom/media/PeerConnectionIdp.jsm b/dom/media/PeerConnectionIdp.jsm
index 0248346e2113..471d09815485 100644
--- a/dom/media/PeerConnectionIdp.jsm
+++ b/dom/media/PeerConnectionIdp.jsm
@@ -56,7 +56,7 @@ PeerConnectionIdp.prototype = {
       }
       this._idp.stop();
     }
-    this._idp = new IdpSandbox(provider, protocol, this._win.document);
+    this._idp = new IdpSandbox(provider, protocol, this._win);
   },
 
   // start the IdP and do some error fixup
diff --git a/dom/media/tests/mochitest/identity/test_fingerprints.html b/dom/media/tests/mochitest/identity/test_fingerprints.html
index ffe6f072c7ab..8aa4ad4ead25 100644
--- a/dom/media/tests/mochitest/identity/test_fingerprints.html
+++ b/dom/media/tests/mochitest/identity/test_fingerprints.html
@@ -12,7 +12,7 @@
 function getIdentityAssertion(fpArray) {
   var Cu = SpecialPowers.Cu;
   var rtcid = Cu.import('resource://gre/modules/media/IdpSandbox.jsm');
-  var sandbox = new rtcid.IdpSandbox('example.com', 'idp.js', window.document);
+  var sandbox = new rtcid.IdpSandbox('example.com', 'idp.js', window);
   return sandbox.start()
     .then(idp => SpecialPowers.wrap(idp)
                    .generateAssertion(JSON.stringify({ fingerprint: fpArray }),
diff --git a/dom/media/tests/mochitest/identity/test_idpproxy.html b/dom/media/tests/mochitest/identity/test_idpproxy.html
index b5d2a3b31158..c8860d1f4e38 100644
--- a/dom/media/tests/mochitest/identity/test_idpproxy.html
+++ b/dom/media/tests/mochitest/identity/test_idpproxy.html
@@ -26,7 +26,7 @@ function test_domain_sandbox() {
                   '', 12, null, diabolical, true ];
   domains.forEach(function(domain) {
     try {
-      var idp = new IdpSandbox(domain, undefined, window.document);
+      var idp = new IdpSandbox(domain, undefined, window);
       ok(false, 'IdpSandbox allowed a bad domain: ' + domain);
     } catch (e) {
       var str = (typeof domain === 'string') ? domain : typeof domain;
@@ -40,7 +40,7 @@ function test_protocol_sandbox() {
                  '\\evil', '%5cevil', 12, true, {} ];
   protos.forEach(function(proto) {
     try {
-      var idp = new IdpSandbox('example.com', proto, window.document);
+      var idp = new IdpSandbox('example.com', proto, window);
       ok(false, 'IdpSandbox allowed a bad protocol: ' + proto);
     } catch (e) {
       var str = (typeof proto === 'string') ? proto : typeof proto;
@@ -56,7 +56,7 @@ function idpName(hash) {
 function makeSandbox(js) {
   var name = js || idpName();
   info('Creating a sandbox for the protocol: ' + name);
-  var sandbox = new IdpSandbox('example.com', name, window.document);
+  var sandbox = new IdpSandbox('example.com', name, window);
   return sandbox.start().then(idp => SpecialPowers.wrap(idp));
 }