Fix intptr_t fallback for Py_ssize_t.
diff --git a/Include/pyport.h b/Include/pyport.h
index f3ba488..9111d86 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -88,7 +88,7 @@
 #ifdef HAVE_SSIZE_T
 typedef ssize_t		Py_ssize_t;
 #elif SIZEOF_VOID_P == SIZEOF_SIZE_T
-typedef Py_uintptr_t	Py_ssize_t;
+typedef Py_intptr_t	Py_ssize_t;
 #else
 #   error "Python needs a typedef for Py_ssize_t in pyport.h."
 #endif