diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index e4ecbe37ee9..9c320ff1edf 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -764,15 +764,14 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
 	/* make sure we have enough WAL available */
 	flushptr = WalSndWaitForWal(targetPagePtr + reqLen);
 
-	/* more than one block available */
-	if (targetPagePtr + XLOG_BLCKSZ <= flushptr)
-		count = XLOG_BLCKSZ;
-	/* not enough WAL synced, that can happen during shutdown */
-	else if (targetPagePtr + reqLen > flushptr)
+	/* fail if not (implies we are going to shut down) */
+	if (flushptr < targetPagePtr + reqLen)
 		return -1;
-	/* part of the page available */
+
+	if (targetPagePtr + XLOG_BLCKSZ <= flushptr)
+		count = XLOG_BLCKSZ;	/* more than one block available */
 	else
-		count = flushptr - targetPagePtr;
+		count = flushptr - targetPagePtr;	/* part of the page available */
 
 	/* now actually read the data, we know it's there */
 	XLogRead(cur_page, targetPagePtr, XLOG_BLCKSZ);
@@ -1158,7 +1157,11 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 }
 
 /*
- * Wait till WAL < loc is flushed to disk so it can be safely read.
+ * Wait till WAL < loc is flushed to disk so it can be safely sent to client.
+ *
+ * Returns end LSN of flushed WAL.  Normally this will be >= loc, but
+ * if we detect a shutdown request (either from postmaster or client)
+ * we will return early, so caller must always check.
  */
 static XLogRecPtr
 WalSndWaitForWal(XLogRecPtr loc)
@@ -1225,9 +1228,7 @@ WalSndWaitForWal(XLogRecPtr loc)
 			RecentFlushPtr = GetXLogReplayRecPtr(NULL);
 
 		/*
-		 * If postmaster asked us to stop, don't wait here anymore. This will
-		 * cause the xlogreader to return without reading a full record, which
-		 * is the fastest way to reach the mainloop which then can quit.
+		 * If postmaster asked us to stop, don't wait anymore.
 		 *
 		 * It's important to do this check after the recomputation of
 		 * RecentFlushPtr, so we can send all remaining data before shutting
@@ -1258,14 +1259,20 @@ WalSndWaitForWal(XLogRecPtr loc)
 		WalSndCaughtUp = true;
 
 		/*
-		 * Try to flush pending output to the client. Also wait for the socket
-		 * becoming writable, if there's still pending output after an attempt
-		 * to flush. Otherwise we might just sit on output data while waiting
-		 * for new WAL being generated.
+		 * Try to flush any pending output to the client.
 		 */
 		if (pq_flush_if_writable() != 0)
 			WalSndShutdown();
 
+		/*
+		 * If we have received CopyDone from the client, sent CopyDone
+		 * ourselves, and the output buffer is empty, it's time to exit
+		 * streaming, so fail the current WAL fetch request.
+		 */
+		if (streamingDoneReceiving && streamingDoneSending &&
+			!pq_is_send_pending())
+			break;
+
 		now = GetCurrentTimestamp();
 
 		/* die if timeout was reached */
@@ -1274,6 +1281,13 @@ WalSndWaitForWal(XLogRecPtr loc)
 		/* Send keepalive if the time has come */
 		WalSndKeepaliveIfNecessary(now);
 
+		/*
+		 * Sleep until something happens or we time out.  Also wait for the
+		 * socket becoming writable, if there's still pending output.
+		 * Otherwise we might sit on sendable output data while waiting for
+		 * new WAL to be generated.  (But if we have nothing to send, we don't
+		 * want to wake on socket-writable.)
+		 */
 		sleeptime = WalSndComputeSleeptime(now);
 
 		wakeEvents = WL_LATCH_SET | WL_POSTMASTER_DEATH |
@@ -1282,7 +1296,6 @@ WalSndWaitForWal(XLogRecPtr loc)
 		if (pq_is_send_pending())
 			wakeEvents |= WL_SOCKET_WRITEABLE;
 
-		/* Sleep until something happens or we time out */
 		WaitLatchOrSocket(MyLatch, wakeEvents,
 						  MyProcPort->sock, sleeptime);
 	}
@@ -1870,7 +1883,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 		 * ourselves, and the output buffer is empty, it's time to exit
 		 * streaming.
 		 */
-		if (!pq_is_send_pending() && streamingDoneSending && streamingDoneReceiving)
+		if (streamingDoneReceiving && streamingDoneSending &&
+			!pq_is_send_pending())
 			break;
 
 		/*