diff --git a/sys/netinet/sctp_constants.h b/sys/netinet/sctp_constants.h
index 66f2cca5ab6d..3df6ad6db2aa 100644
--- a/sys/netinet/sctp_constants.h
+++ b/sys/netinet/sctp_constants.h
@@ -968,7 +968,7 @@ __FBSDID("$FreeBSD$");
 #define sctp_sowwakeup(inp, so) \
 do { \
 	if (inp->sctp_flags & SCTP_PCB_FLAGS_DONT_WAKE) { \
-		inp->sctp_flags |= SCTP_PCB_FLAGS_WAKEOUTPUT; \
+		sctp_pcb_add_flags(inp, SCTP_PCB_FLAGS_WAKEOUTPUT); \
 	} else { \
 		sowwakeup(so); \
 	} \
@@ -977,8 +977,8 @@ do { \
 #define sctp_sowwakeup_locked(inp, so) \
 do { \
 	if (inp->sctp_flags & SCTP_PCB_FLAGS_DONT_WAKE) { \
+		sctp_pcb_add_flags(inp, SCTP_PCB_FLAGS_WAKEOUTPUT); \
 		SOCKBUF_UNLOCK(&((so)->so_snd)); \
-		inp->sctp_flags |= SCTP_PCB_FLAGS_WAKEOUTPUT; \
 	} else { \
 		sowwakeup_locked(so); \
 	} \
@@ -987,7 +987,7 @@ do { \
 #define sctp_sorwakeup(inp, so) \
 do { \
 	if (inp->sctp_flags & SCTP_PCB_FLAGS_DONT_WAKE) { \
-		inp->sctp_flags |= SCTP_PCB_FLAGS_WAKEINPUT; \
+		sctp_pcb_add_flags(inp, SCTP_PCB_FLAGS_WAKEINPUT); \
 	} else { \
 		sorwakeup(so); \
 	} \
@@ -996,7 +996,7 @@ do { \
 #define sctp_sorwakeup_locked(inp, so) \
 do { \
 	if (inp->sctp_flags & SCTP_PCB_FLAGS_DONT_WAKE) { \
-		inp->sctp_flags |= SCTP_PCB_FLAGS_WAKEINPUT; \
+		sctp_pcb_add_flags(inp, SCTP_PCB_FLAGS_WAKEINPUT); \
 		SOCKBUF_UNLOCK(&((so)->so_rcv)); \
 	} else { \
 		sorwakeup_locked(so); \
diff --git a/sys/netinet/sctp_input.c b/sys/netinet/sctp_input.c
index ff16654968d5..46b818c9983e 100644
--- a/sys/netinet/sctp_input.c
+++ b/sys/netinet/sctp_input.c
@@ -1491,8 +1491,7 @@ sctp_process_cookie_existing(struct mbuf *m, int iphlen, int offset,
 				 * init/init-ack/cookie done before the
 				 * init-ack came back..
 				 */
-				stcb->sctp_ep->sctp_flags |=
-				    SCTP_PCB_FLAGS_CONNECTED;
+				sctp_pcb_add_flags(stcb->sctp_ep, SCTP_PCB_FLAGS_CONNECTED);
 				soisconnected(stcb->sctp_socket);
 			}
 			/* notify upper layer */
@@ -1689,7 +1688,7 @@ sctp_process_cookie_existing(struct mbuf *m, int iphlen, int offset,
 			if (((stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_TCPTYPE) ||
 			    (stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_IN_TCPPOOL)) &&
 			    (!SCTP_IS_LISTENING(inp))) {
-				stcb->sctp_ep->sctp_flags |= SCTP_PCB_FLAGS_CONNECTED;
+				sctp_pcb_add_flags(stcb->sctp_ep, SCTP_PCB_FLAGS_CONNECTED);
 				soisconnected(stcb->sctp_socket);
 			}
 			if (SCTP_GET_STATE(stcb) == SCTP_STATE_COOKIE_ECHOED)
@@ -2182,7 +2181,7 @@ sctp_process_cookie_new(struct mbuf *m, int iphlen, int offset,
 		 *
 		 * XXXMJ unlocked
 		 */
-		stcb->sctp_ep->sctp_flags |= SCTP_PCB_FLAGS_CONNECTED;
+		sctp_pcb_add_flags(stcb->sctp_ep, SCTP_PCB_FLAGS_CONNECTED);
 		soisconnected(stcb->sctp_socket);
 	} else if ((stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_TCPTYPE) &&
 	    (SCTP_IS_LISTENING(inp))) {
@@ -2793,7 +2792,7 @@ sctp_handle_cookie_ack(struct sctp_cookie_ack_chunk *cp SCTP_UNUSED,
 		sctp_ulp_notify(SCTP_NOTIFY_ASSOC_UP, stcb, 0, NULL, SCTP_SO_NOT_LOCKED);
 		if ((stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_TCPTYPE) ||
 		    (stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_IN_TCPPOOL)) {
-			stcb->sctp_ep->sctp_flags |= SCTP_PCB_FLAGS_CONNECTED;
+			sctp_pcb_add_flags(stcb->sctp_ep, SCTP_PCB_FLAGS_CONNECTED);
 			if ((stcb->asoc.state & SCTP_STATE_CLOSED_SOCKET) == 0) {
 				soisconnected(stcb->sctp_socket);
 			}
diff --git a/sys/netinet/sctp_pcb.c b/sys/netinet/sctp_pcb.c
index 38c88d8ae8e4..bbbec5385c3c 100644
--- a/sys/netinet/sctp_pcb.c
+++ b/sys/netinet/sctp_pcb.c
@@ -7067,3 +7067,18 @@ sctp_initiate_iterator(inp_func inpf,
 	/* sa_ignore MEMLEAK {memory is put on the tailq for the iterator} */
 	return (0);
 }
+
+/*
+ * Atomically add flags to the sctp_flags of an inp.
+ * To be used when the write lock of the inp is not held.
+ */
+void
+sctp_pcb_add_flags(struct sctp_inpcb *inp, uint32_t flags)
+{
+	uint32_t old_flags, new_flags;
+
+	do {
+		old_flags = inp->sctp_flags;
+		new_flags = old_flags | flags;
+	} while (atomic_cmpset_int(&inp->sctp_flags, old_flags, new_flags) == 0);
+}
diff --git a/sys/netinet/sctp_pcb.h b/sys/netinet/sctp_pcb.h
index 736b0f9d54e9..687ccf6a1c50 100644
--- a/sys/netinet/sctp_pcb.h
+++ b/sys/netinet/sctp_pcb.h
@@ -619,6 +619,9 @@ int sctp_swap_inpcb_for_listen(struct sctp_inpcb *inp);
 
 void sctp_clean_up_stream(struct sctp_tcb *stcb, struct sctp_readhead *rh);
 
+void
+     sctp_pcb_add_flags(struct sctp_inpcb *, uint32_t);
+
 /*-
  * Null in last arg inpcb indicate run on ALL ep's. Specific inp in last arg
  * indicates run on ONLY assoc's of the specified endpoint.
diff --git a/sys/netinet/sctputil.c b/sys/netinet/sctputil.c
index 23f95353323f..bdb35b988ae6 100644
--- a/sys/netinet/sctputil.c
+++ b/sys/netinet/sctputil.c
@@ -4340,7 +4340,7 @@ sctp_abort_notification(struct sctp_tcb *stcb, bool from_peer, bool timeout,
 	if ((stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_IN_TCPPOOL) ||
 	    ((stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_TCPTYPE) &&
 	    (stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_CONNECTED))) {
-		stcb->sctp_ep->sctp_flags |= SCTP_PCB_FLAGS_WAS_ABORTED;
+		sctp_pcb_add_flags(stcb->sctp_ep, SCTP_PCB_FLAGS_WAS_ABORTED);
 	}
 	if ((stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_SOCKET_GONE) ||
 	    (stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_SOCKET_ALLGONE) ||