diff --git a/telnet/libtelnet/encrypt.c b/telnet/libtelnet/encrypt.c
index f75317d..b8d6cdd 100644
--- a/telnet/libtelnet/encrypt.c
+++ b/telnet/libtelnet/encrypt.c
@@ -757,6 +757,9 @@ static void encrypt_keyid(kp, keyid, len)
 	int dir = kp->dir;
 	register int ret = 0;
 
+	if (len > MAXKEYLEN)
+		len = MAXKEYLEN;
+
 	if (!(ep = (*kp->getcrypt)(*kp->modep))) {
 		if (len == 0)
 			return;