diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index ae08c563c712..a996dd5bb0c2 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1614,9 +1614,13 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	int ret = 0;
 	long timeo;
 
-	if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL))
+	/* we don't support FASTOPEN yet */
+	if (msg->msg_flags & MSG_FASTOPEN)
 		return -EOPNOTSUPP;
 
+	/* silently ignore everything else */
+	msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL;
+
 	mptcp_lock_sock(sk, __mptcp_wmem_reserve(sk, min_t(size_t, 1 << 20, len)));
 
 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
@@ -1951,9 +1955,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	if (unlikely(flags & MSG_ERRQUEUE))
 		return inet_recv_error(sk, msg, len, addr_len);
 
-	if (msg->msg_flags & ~(MSG_WAITALL | MSG_DONTWAIT))
-		return -EOPNOTSUPP;
-
 	mptcp_lock_sock(sk, __mptcp_splice_receive_queue(sk));
 	if (unlikely(sk->sk_state == TCP_LISTEN)) {
 		copied = -ENOTCONN;