--- a/pppd/chap_ms.c
+++ b/pppd/chap_ms.c
@@ -852,7 +852,7 @@ ChapMS2(u_char *rchallenge, u_char *Peer
u_char *p = &response[MS_CHAP2_PEER_CHALLENGE];
int i;
- BZERO(response, sizeof(*response));
+ BZERO(response, MS_CHAP2_RESPONSE_LEN);
/* Generate the Peer-Challenge if requested, or copy it if supplied. */
if (!PeerChallenge)
