diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index b3b24de94f5..8d524926b89 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1282,9 +1282,9 @@ def __format__(self, format_spec):
         self.assertRaises(IndexError, u"{:}".format)
         self.assertRaises(IndexError, u"{:s}".format)
         self.assertRaises(IndexError, u"{}".format)
-        big = "23098475029384702983476098230754973209482573"
-        self.assertRaises(ValueError, ("{" + big + "}").format)
-        self.assertRaises(ValueError, ("{[" + big + "]}").format, [0])
+        big = u"23098475029384702983476098230754973209482573"
+        self.assertRaises(ValueError, (u"{" + big + u"}").format)
+        self.assertRaises(ValueError, (u"{[" + big + u"]}").format, [0])
 
         # issue 6089
         self.assertRaises(ValueError, u"{0[0]x}".format, [None])