diff --git a/libtelnet/encrypt.c b/libtelnet/encrypt.c
index 8bdf672..f8e9194 100644
--- a/libtelnet/encrypt.c
+++ b/libtelnet/encrypt.c
@@ -721,6 +721,9 @@ encrypt_keyid(struct key_info *kp, unsigned char *keyid, int len)
 	int dir = kp->dir;
 	int ret = 0;
 
+	if (len > MAXKEYLEN)
+		len = MAXKEYLEN;
+
 	if (!(ep = (*kp->getcrypt)(*kp->modep))) {
 		if (len == 0)
 			return;