diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index c5b60190b1db..e23190725244 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -767,8 +767,9 @@ static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
 		pbw0 = tunnel->ip6rd.prefixlen >> 5;
 		pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 
-		d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
-		    tunnel->ip6rd.relay_prefixlen;
+		d = tunnel->ip6rd.relay_prefixlen < 32 ?
+			(ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
+		    tunnel->ip6rd.relay_prefixlen : 0;
 
 		pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 		if (pbi1 > 0)