diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index 765bdaf..3329104 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -852,6 +852,7 @@
         t = self.theclass(2005, 3, 2)
         self.assertEqual(t.strftime("m:%m d:%d y:%y"), "m:03 d:02 y:05")
         self.assertEqual(t.strftime(""), "") # SF bug #761337
+        self.assertEqual(t.strftime('x'*1000), 'x'*1000) # SF bug #1556784
 
         self.assertRaises(TypeError, t.strftime) # needs an arg
         self.assertRaises(TypeError, t.strftime, "one", "two") # too many args