diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e9aa6807b5be..3c19a8efdcea 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -543,6 +543,11 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 	}
 }
 
+static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
+{
+	return 0;
+}
+
 static int __mptcp_init_sock(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
@@ -551,6 +556,7 @@ static int __mptcp_init_sock(struct sock *sk)
 	__set_bit(MPTCP_SEND_SPACE, &msk->flags);
 
 	msk->first = NULL;
+	inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
 
 	return 0;
 }