Correct code to advance ptr to be well-formed C.
diff --git a/Objects/bufferobject.c b/Objects/bufferobject.c
index a5aa523..6adf838 100644
--- a/Objects/bufferobject.c
+++ b/Objects/bufferobject.c
@@ -43,7 +43,7 @@
 			offset = count;
 		else
 			offset = self->b_offset;
-		(char *)*ptr = (char *)*ptr + offset;
+		*(char **)ptr = *(char **)ptr + offset;
 		if (self->b_size == Py_END_OF_BUFFER)
 			*size = count;
 		else