1 files changed, 1 insertions, 1 deletions
diff --git a/ndp.c b/ndp.c
index 74445ad..a1d76c1 100644
--- a/ndp.c
+++ b/ndp.c
@@ -116,7 +116,7 @@ int ndp(struct ctx *c, struct ethhdr *eh, size_t len)
 		memcpy(p, &c->addr6, 8);	/* prefix */
 		p += 16;
 
-		if (c->mtu) {
+		if (c->mtu != -1) {
 			*p++ = 5;			/* type */
 			*p++ = 1;			/* length */
 			p += 2;				/* reserved */