diff --git a/Include/allobjects.h b/Include/allobjects.h
index 5ce324d..34b3816 100644
--- a/Include/allobjects.h
+++ b/Include/allobjects.h
@@ -82,6 +82,14 @@
 #define PyArg_GetInt(v, a)	PyArg_Parse((v), "i", (a))
 #define PyArg_NoArgs(v)		PyArg_Parse(v, "")
 
+/* 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)
+#else
+#define Py_CHARMASK(c)		((c) & 0xff)
+#endif
+
 #ifdef __cplusplus
 }
 #endif