diff --git a/toolkit/mozapps/extensions/content/extensions.js b/toolkit/mozapps/extensions/content/extensions.js
index ec1c7c16f27..8cd2d0511a1 100644
--- a/toolkit/mozapps/extensions/content/extensions.js
+++ b/toolkit/mozapps/extensions/content/extensions.js
@@ -3292,8 +3292,8 @@ var gDragDrop = {
       if (pos == urls.length) {
         if (installs.length > 0) {
           // Display the normal install confirmation for the installs
-          AddonManager.installAddonsFromWebpage("application/x-xpinstall", this,
-                                                null, installs);
+          AddonManager.installAddonsFromWebpage("application/x-xpinstall",
+                                                window, null, installs);
         }
         return;
       }
diff --git a/toolkit/mozapps/extensions/test/browser/browser_dragdrop.js b/toolkit/mozapps/extensions/test/browser/browser_dragdrop.js
index ad02c1842ec..ea70defc31e 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_dragdrop.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_dragdrop.js
@@ -75,6 +75,17 @@ WindowOpenListener.prototype = {
   }
 };
 
+var gSawInstallNotification = false;
+var gInstallNotificationObserver = {
+  observe: function(aSubject, aTopic, aData) {
+    var installInfo = aSubject.QueryInterface(Ci.amIWebInstallInfo);
+    isnot(installInfo.originatingWindow, null, "Notification should have non-null originatingWindow");
+    gSawInstallNotification = true;
+    Services.obs.removeObserver(this, "addon-install-started");
+  }
+};
+
+
 function test() {
   waitForExplicitFinish();
 
@@ -113,9 +124,15 @@ function test_confirmation(aWindow, aExpectedURLs) {
 add_test(function() {
   var url = TESTROOT + "addons/browser_dragdrop1.xpi";
 
+  Services.obs.addObserver(gInstallNotificationObserver,
+                           "addon-install-started", false);
+
   new WindowOpenListener(INSTALL_URI, function(aWindow) {
     test_confirmation(aWindow, [url]);
-  }, run_next_test);
+  }, function() {
+    is(gSawInstallNotification, true, "Should have seen addon-install-started notification.");
+    run_next_test();
+  });
 
   var viewContainer = gManagerWindow.document.getElementById("view-port");
   var effect = chromeUtils.synthesizeDrop(viewContainer, viewContainer,
@@ -128,9 +145,15 @@ add_test(function() {
 add_test(function() {
   var fileurl = get_addon_file_url("browser_dragdrop1.xpi");
 
+  Services.obs.addObserver(gInstallNotificationObserver,
+                           "addon-install-started", false);
+
   new WindowOpenListener(INSTALL_URI, function(aWindow) {
     test_confirmation(aWindow, [fileurl.spec]);
-  }, run_next_test);
+  }, function() {
+    is(gSawInstallNotification, true, "Should have seen addon-install-started notification.");
+    run_next_test();
+  });
 
   var viewContainer = gManagerWindow.document.getElementById("view-port");
   var effect = chromeUtils.synthesizeDrop(viewContainer, viewContainer,
@@ -144,9 +167,15 @@ add_test(function() {
   var url1 = TESTROOT + "addons/browser_dragdrop1.xpi";
   var url2 = TESTROOT2 + "addons/browser_dragdrop2.xpi";
 
+  Services.obs.addObserver(gInstallNotificationObserver,
+                           "addon-install-started", false);
+
   new WindowOpenListener(INSTALL_URI, function(aWindow) {
     test_confirmation(aWindow, [url1, url2]);
-  }, run_next_test);
+  }, function() {
+    is(gSawInstallNotification, true, "Should have seen addon-install-started notification.");
+    run_next_test();
+  });
 
   var viewContainer = gManagerWindow.document.getElementById("view-port");
   var effect = chromeUtils.synthesizeDrop(viewContainer, viewContainer,
@@ -161,9 +190,15 @@ add_test(function() {
   var fileurl1 = get_addon_file_url("browser_dragdrop1.xpi");
   var fileurl2 = get_addon_file_url("browser_dragdrop2.xpi");
 
+  Services.obs.addObserver(gInstallNotificationObserver,
+                           "addon-install-started", false);
+
   new WindowOpenListener(INSTALL_URI, function(aWindow) {
     test_confirmation(aWindow, [fileurl1.spec, fileurl2.spec]);
-  }, run_next_test);
+  }, function() {
+    is(gSawInstallNotification, true, "Should have seen addon-install-started notification.");
+    run_next_test();
+  });
 
   var viewContainer = gManagerWindow.document.getElementById("view-port");
   var effect = chromeUtils.synthesizeDrop(viewContainer, viewContainer,
@@ -178,9 +213,15 @@ add_test(function() {
   var url = TESTROOT + "addons/browser_dragdrop1.xpi";
   var fileurl = get_addon_file_url("browser_dragdrop2.xpi");
 
+  Services.obs.addObserver(gInstallNotificationObserver,
+                           "addon-install-started", false);
+
   new WindowOpenListener(INSTALL_URI, function(aWindow) {
     test_confirmation(aWindow, [url, fileurl.spec]);
-  }, run_next_test);
+  }, function() {
+    is(gSawInstallNotification, true, "Should have seen addon-install-started notification.");
+    run_next_test();
+  });
 
   var viewContainer = gManagerWindow.document.getElementById("view-port");
   var effect = chromeUtils.synthesizeDrop(viewContainer, viewContainer,