diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index a39f373fa15..b671c434a3e 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -2488,13 +2488,14 @@ WalSndDone(WalSndSendDataCallback send_data)
 	send_data();
 
 	/*
-	 * Check a write location to see whether all the WAL have successfully
-	 * been replicated if this walsender is connecting to a standby such as
-	 * pg_receivexlog which always returns an invalid flush location.
-	 * Otherwise, check a flush location.
+	 * To figure out whether all WAL has successfully been replicated, check
+	 * flush location if valid, write otherwise. Tools like pg_receivexlog
+	 * will usually (unless in synchronous mode) return an invalid flush
+	 * location.
 	 */
 	replicatedPtr = XLogRecPtrIsInvalid(MyWalSnd->flush) ?
 		MyWalSnd->write : MyWalSnd->flush;
+
 	if (WalSndCaughtUp && sentPtr == replicatedPtr &&
 		!pq_is_send_pending())
 	{
@@ -2505,7 +2506,10 @@ WalSndDone(WalSndSendDataCallback send_data)
 		proc_exit(0);
 	}
 	if (!waiting_for_ping_response)
+	{
 		WalSndKeepalive(true);
+		waiting_for_ping_response = true;
+	}
 }
 
 /*