diff -r 1d87ac92b041 Lib/test/support/__init__.py
--- a/Lib/test/support/__init__.py	Fri Oct 31 01:37:03 2014 +0200
+++ b/Lib/test/support/__init__.py	Fri Oct 31 10:59:29 2014 +0200
@@ -461,12 +461,14 @@ def _is_gui_available():
                 reason = "cannot run without OS X gui process"
 
     # check on every platform whether tkinter can actually do anything
-    # but skip the test on OS X because it can cause segfaults in Cocoa Tk
-    # when running regrtest with the -j option (multiple threads/subprocesses)
-    if (not reason) and (sys.platform != 'darwin'):
+    if not reason:
         try:
-            from tkinter import Tk
+            from tkinter import Tk, Label
             root = Tk()
+            w = Label(root, text='Test')
+            w.pack()
+            root.update()
+            w.destroy()
             root.destroy()
         except Exception as e:
             err_string = str(e)