diff --git a/mongoose.c b/mongoose.c
index d1aa09ca..98d43685 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -10246,6 +10246,7 @@ static struct mg_connection *getpeer(struct mg_mgr *mgr, struct pkt *pkt,
     if (!c->is_udp && pkt->tcp && c->loc.port == pkt->tcp->dport &&
         ((lsn && c->is_listening && !(c->loc.is_ip6 ^ (pkt->ip6 != NULL))) ||
          (!lsn && !c->is_listening && c->rem.port == pkt->tcp->sport &&
+          !(c->loc.is_ip6 ^ (pkt->ip6 != NULL)) &&  // IP or IPv6 to same dest
           ((!c->loc.is_ip6 && c->rem.addr.ip4 == pkt->ip->src)
 #if MG_ENABLE_IPV6
            || (c->loc.is_ip6 && MG_IP6MATCH(c->rem.addr.ip6, pkt->ip6->src))
diff --git a/src/net_builtin.c b/src/net_builtin.c
index ac072485..3cc379cb 100644
--- a/src/net_builtin.c
+++ b/src/net_builtin.c
@@ -602,6 +602,7 @@ static struct mg_connection *getpeer(struct mg_mgr *mgr, struct pkt *pkt,
     if (!c->is_udp && pkt->tcp && c->loc.port == pkt->tcp->dport &&
         ((lsn && c->is_listening && !(c->loc.is_ip6 ^ (pkt->ip6 != NULL))) ||
          (!lsn && !c->is_listening && c->rem.port == pkt->tcp->sport &&
+          !(c->loc.is_ip6 ^ (pkt->ip6 != NULL)) &&  // IP or IPv6 to same dest
           ((!c->loc.is_ip6 && c->rem.addr.ip4 == pkt->ip->src)
 #if MG_ENABLE_IPV6
            || (c->loc.is_ip6 && MG_IP6MATCH(c->rem.addr.ip6, pkt->ip6->src))