diff -r 6cd736239b8a -r dd3992754141 Lib/test/test_types.py
--- a/Lib/test/test_types.py	Sat Dec 10 21:25:04 2011 +0100
+++ b/Lib/test/test_types.py	Sat Dec 10 22:20:23 2011 +0100
@@ -340,6 +340,8 @@
         self.assertRaises(ValueError, 3 .__format__, ",n")
         # can't have ',' with 'c'
         self.assertRaises(ValueError, 3 .__format__, ",c")
+        # can't have '#' with 'c'
+        self.assertRaises(ValueError, 3 .__format__, "#c")
 
         # ensure that only int and float type specifiers work
         for format_spec in ([chr(x) for x in range(ord('a'), ord('z')+1)] +
diff -r 6cd736239b8a -r dd3992754141 Python/formatter_unicode.c
--- a/Python/formatter_unicode.c	Sat Dec 10 21:25:04 2011 +0100
+++ b/Python/formatter_unicode.c	Sat Dec 10 22:20:23 2011 +0100
@@ -792,6 +792,13 @@
                             " format specifier 'c'");
             goto done;
         }
+        /* error to request alternate format */
+        if (format->alternate) {
+            PyErr_SetString(PyExc_ValueError,
+                            "Alternate form (#) not allowed with integer"
+                            " format specifier 'c'");
+            goto done;
+        }
 
         /* taken from unicodeobject.c formatchar() */
         /* Integer input truncated to a character */