Index: Include/Python.h
===================================================================
--- Include/Python.h	(revision 82072)
+++ Include/Python.h	(working copy)
@@ -153,7 +153,7 @@
 /* Convert a possibly signed character to a nonnegative int */
 /* XXX This assumes characters are 8 bits wide */
 #ifdef __CHAR_UNSIGNED__
-#define Py_CHARMASK(c)		(c)
+#define Py_CHARMASK(c)		((char)(c))
 #else
 #define Py_CHARMASK(c)		((unsigned char)((c) & 0xff))
 #endif