diff --git a/Include/codecs.h b/Include/codecs.h
index dff09e7..c503f5c 100644
--- a/Include/codecs.h
+++ b/Include/codecs.h
@@ -174,6 +174,8 @@
 /* replace the unicode encode error with backslash escapes (\x, \u and \U) */
 PyAPI_FUNC(PyObject *) PyCodec_BackslashReplaceErrors(PyObject *exc);
 
+extern const char *Py_hexdigits;
+
 #ifdef __cplusplus
 }
 #endif