diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index be6f391..c5bb54a 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -558,6 +558,10 @@
         # TypeError because self.__format__ returns the wrong type
         self.assertRaises(TypeError, format, B(), "")
 
+        # TypeError because format_spec is not unicode
+        self.assertRaises(TypeError, format, object(), 4)
+        self.assertRaises(TypeError, format, object(), object())
+
         # make sure we can take a subclass of str as a format spec
         self.assertEqual(format(0, C('10')), '         0')
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 2a0dd24..682c029 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2950,12 +2950,8 @@
         PyObject *result = NULL;
         PyObject *format_meth = NULL;
 
-        if (!PyArg_ParseTuple(args, "O:__format__", &format_spec))
+        if (!PyArg_ParseTuple(args, "U:__format__", &format_spec))
                 return NULL;
-        if (!PyUnicode_Check(format_spec)) {
-                PyErr_SetString(PyExc_TypeError, "Unicode object required");
-                return NULL;
-        }
 
         self_as_str = PyObject_Str(self);
         if (self_as_str != NULL) {