diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 684ae8650c19..f4604611f10f 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -226,6 +226,7 @@ static bool subflow_in_rm_list(const struct mptcp_subflow_context *subflow,
 	return false;
 }
 
+static void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk);
 static void
 mptcp_pm_addr_send_ack_avoid_list(struct mptcp_sock *msk,
 				  const struct mptcp_rm_list *rm_list)
@@ -743,7 +744,8 @@ void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk,
 	spin_unlock_bh(&pm->lock);
 }
 
-void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk)
+/* To be called while pm->lock is held */
+static void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk)
 {
 	if (!mptcp_pm_should_add_signal(msk))
 		return;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 8bfb351c6257..7bc8fd486e81 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1114,7 +1114,6 @@ void mptcp_pm_add_addr_received(const struct sock *ssk,
 				const struct mptcp_addr_info *addr);
 void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk,
 			      const struct mptcp_addr_info *addr);
-void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk);
 void mptcp_pm_send_ack(struct mptcp_sock *msk,
 		       struct mptcp_subflow_context *subflow,
 		       bool prio, bool backup);