--- libaitcrc/src/pelco.c	2012/07/04 14:46:33	1.3.2.2
+++ libaitcrc/src/pelco.c	2012/07/04 14:52:57	1.3.2.3
@@ -3,7 +3,7 @@
 *  by Michael Pounov <misho@openbsd-bg.org>
 *
 * $Author: misho $
-* $Id: pelco.c,v 1.3.2.2 2012/07/04 14:46:33 misho Exp $
+* $Id: pelco.c,v 1.3.2.3 2012/07/04 14:52:57 misho Exp $
 *
 **************************************************************************
 The ELWIX and AITNET software is distributed under the following
@@ -58,6 +58,8 @@ inline u_char
 crcPelco(u_char ver, u_char *pkt)
 {
 	register u_char i, crc;
+
+	assert(pkt);
 
 	switch (ver) {
 		case 'D':