--- a/testing/web-platform/tests/webdriver/tests/support/fixtures.py
+++ b/testing/web-platform/tests/webdriver/tests/support/fixtures.py
@@ -3,16 +3,17 @@ import os
 import urlparse
 import re
 
 import webdriver
 import mozlog
 
 from tests.support.asserts import assert_error
 from tests.support.http_request import HTTPRequest
+from tests.support.wait import wait
 from tests.support import merge_dictionaries
 
 default_host = "http://127.0.0.1"
 default_port = "4444"
 
 logger = mozlog.get_default_logger()
 
 
@@ -241,15 +242,28 @@ def create_dialog(session):
             setTimeout(function() {{
                 window.{0} = window.{1}("{2}");
             }}, 0);
         """.format(result_var, dialog_type, text)
 
         session.send_session_command("POST",
                                      "execute/async",
                                      {"script": spawn, "args": []})
+        import datetime
+        print("waiting time is {}".format(datetime.datetime.now()))
+        try:
+            wait(session,
+                lambda s:s.send_session_command("GET", "alert/text"),
+                "modal has not appeared", timeout=15)
+            print("waiting time is {}".format(datetime.datetime.now()))
+
+        except:
+            print session.send_session_command("POST",
+                                         "execute/sync",
+                                         {"script": "return window.__WEBDRIVER == undefined", "args": []})
+
+
 
     return create_dialog
 
 def clear_all_cookies(session):
     """Removes all cookies associated with the current active document"""
     session.transport.send("DELETE", "session/%s/cookie" % session.session_id)
-