diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index c9643344a8d7..17ad42c65087 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -699,10 +699,11 @@ static bool mptcp_established_options_mp_prio(struct sock *sk,
 	if (!subflow->send_mp_prio)
 		return false;
 
-	if (remaining < TCPOLEN_MPTCP_PRIO)
+	/* account for the trailing 'nop' option */
+	if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
 		return false;
 
-	*size = TCPOLEN_MPTCP_PRIO;
+	*size = TCPOLEN_MPTCP_PRIO_ALIGN;
 	opts->suboptions |= OPTION_MPTCP_PRIO;
 	opts->backup = subflow->request_bkup;
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 1460705aaad0..07ee319f7847 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -60,7 +60,8 @@
 #define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT	24
 #define TCPOLEN_MPTCP_PORT_LEN		4
 #define TCPOLEN_MPTCP_RM_ADDR_BASE	4
-#define TCPOLEN_MPTCP_PRIO		4
+#define TCPOLEN_MPTCP_PRIO		3
+#define TCPOLEN_MPTCP_PRIO_ALIGN	4
 #define TCPOLEN_MPTCP_FASTCLOSE		12
 
 /* MPTCP MP_JOIN flags */