diff --git a/src/backend/replication/syncrep.c b/src/backend/replication/syncrep.c
index 6a28becdad5..77e80f16123 100644
--- a/src/backend/replication/syncrep.c
+++ b/src/backend/replication/syncrep.c
@@ -293,8 +293,11 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
 	 * WalSender has checked our LSN and has removed us from queue. Clean up
 	 * state and leave.  It's OK to reset these shared memory fields without
 	 * holding SyncRepLock, because any walsenders will ignore us anyway when
-	 * we're not on the queue.
+	 * we're not on the queue.  We need a read barrier to make sure we see
+	 * the changes to the queue link (this might be unnecessary without
+	 * assertions, but better safe than sorry).
 	 */
+	pg_read_barrier();
 	Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
 	MyProc->syncRepState = SYNC_REP_NOT_WAITING;
 	MyProc->waitLSN = 0;
@@ -1021,17 +1024,24 @@ SyncRepWakeQueue(bool all, int mode)
 									   &(proc->syncRepLinks),
 									   offsetof(PGPROC, syncRepLinks));
 
+		/*
+		 * Remove thisproc from queue.
+		 */
+		SHMQueueDelete(&(thisproc->syncRepLinks));
+
+		/*
+		 * SyncRepWaitForLSN() reads syncRepState without holding the lock, so
+		 * make sure that it sees the queue link being removed before the
+		 * syncRepState change.
+		 */
+		pg_write_barrier();
+
 		/*
 		 * Set state to complete; see SyncRepWaitForLSN() for discussion of
 		 * the various states.
 		 */
 		thisproc->syncRepState = SYNC_REP_WAIT_COMPLETE;
 
-		/*
-		 * Remove thisproc from queue.
-		 */
-		SHMQueueDelete(&(thisproc->syncRepLinks));
-
 		/*
 		 * Wake only when we have set state and removed from queue.
 		 */