diff --git a/net/bootp.c b/net/bootp.c
index 3c0614c..f48744a 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -313,7 +313,7 @@
 	Bootp_t *bp;
 	char	*s;
 
-	debug ("got BOOTP packet (src=%d, dst=%d, len=%d want_len=%d)\n",
+	debug ("got BOOTP packet (src=%d, dst=%d, len=%d want_len=%zu)\n",
 		src, dest, len, sizeof (Bootp_t));
 
 	bp = (Bootp_t *)pkt;