diff --git a/src/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c
index 595213f..94f1f37 100644
--- a/src/bin/pg_basebackup/receivelog.c
+++ b/src/bin/pg_basebackup/receivelog.c
@@ -509,7 +509,7 @@ ReceiveXlogStream(PGconn *conn, StreamCtl *stream)
 		 * Report the flush position, so the primary can know what WAL we'll
 		 * possibly re-request, and remove older WAL safely.
 		 *
-		 * We only report it when a slot has explicitly been used, because
+		 * We always report it when a slot has explicitly been used, because
 		 * reporting the flush position makes one eligible as a synchronous
 		 * replica. People shouldn't include generic names in
 		 * synchronous_standby_names, but we've protected them against it so
@@ -522,7 +522,14 @@ ReceiveXlogStream(PGconn *conn, StreamCtl *stream)
 	}
 	else
 	{
-		reportFlushPosition = false;
+		/*
+		 * If 'synchronous' is true, report flush position unconditionally
+		 * to make pg_receivexlog eligible as a synchronous replica.
+		 */
+		if (stream->synchronous)
+			reportFlushPosition = true;
+		else
+			reportFlushPosition = false;
 		slotcmd[0] = 0;
 	}