diff --git a/weed/server/master_grpc_server.go b/weed/server/master_grpc_server.go
index d45ee860e..15cac59f6 100644
--- a/weed/server/master_grpc_server.go
+++ b/weed/server/master_grpc_server.go
@@ -418,7 +418,7 @@ func (ms *MasterServer) KeepConnected(stream master_pb.Seaweed_KeepConnectedServ
 		if req.ClientType == cluster.FilerType {
 			ms.LockRingManager.RemoveServer(cluster.FilerGroupName(req.FilerGroup), peerAddress)
 		}
-		ms.deleteClient(clientName)
+		ms.deleteClient(clientName, messageChan)
 	}()
 
 	// Send volume locations to the client
@@ -481,7 +481,12 @@ func (ms *MasterServer) KeepConnected(stream master_pb.Seaweed_KeepConnectedServ
 	defer ticker.Stop()
 	for {
 		select {
-		case message := <-messageChan:
+		case message, ok := <-messageChan:
+			if !ok {
+				// a closed channel receives nil forever; without this check the
+				// loop would flood the client with empty messages at wire speed
+				return nil
+			}
 			if err := stream.Send(message); err != nil {
 				// The error, not the message: it carries every volume id on a
 				// newly connected node, and formatting a proto that size to
@@ -582,14 +587,18 @@ func (ms *MasterServer) addClient(filerGroup, clientType string, clientAddress p
 	return
 }
 
-func (ms *MasterServer) deleteClient(clientName string) {
+func (ms *MasterServer) deleteClient(clientName string, messageChan chan *master_pb.KeepConnectedResponse) {
 	glog.V(0).Infof("- client %v", clientName)
 	ms.clientChansLock.Lock()
-	// close message chan, so that the KeepConnected go routine can exit
-	if clientChan, ok := ms.clientChans[clientName]; ok {
-		close(clientChan)
+	// a client that reconnects before the old handler exits re-registers the
+	// same name, so the map may already hold the new stream's channel: close
+	// only our own, and leave the entry alone unless it is still ours
+	if ms.clientChans[clientName] == messageChan {
 		delete(ms.clientChans, clientName)
 	}
+	// safe under the write lock: broadcasters send while holding the read
+	// lock and only to channels found in the map
+	close(messageChan)
 	ms.clientChansLock.Unlock()
 }
 
diff --git a/weed/server/master_grpc_server_test.go b/weed/server/master_grpc_server_test.go
index fb12f5dc9..7822078a4 100644
--- a/weed/server/master_grpc_server_test.go
+++ b/weed/server/master_grpc_server_test.go
@@ -38,6 +38,50 @@ func TestInitialLockRingUpdateSkipsNonFilers(t *testing.T) {
 	assert.Nil(t, ms.initialLockRingUpdate(cluster.BrokerType, "group-a"))
 }
 
+// TestReconnectedClientSurvivesOldHandlerCleanup covers a client reconnecting
+// KeepConnected under the same name before the old handler has exited: the old
+// handler's deferred cleanup must not close the channel the reconnected stream
+// registered, or that stream reads nil from its closed channel forever and
+// floods the client with empty responses.
+func TestReconnectedClientSurvivesOldHandlerCleanup(t *testing.T) {
+	ms := &MasterServer{
+		clientChans: make(map[string]chan *master_pb.KeepConnectedResponse),
+	}
+
+	clientName, oldChan := ms.addClient("", cluster.MasterType, "peer:19333")
+	_, newChan := ms.addClient("", cluster.MasterType, "peer:19333")
+
+	// the old handler's deferred cleanup runs after the reconnect registered
+	ms.deleteClient(clientName, oldChan)
+
+	// the old channel is closed so its drain goroutine can exit
+	select {
+	case _, ok := <-oldChan:
+		assert.False(t, ok, "old channel should be closed")
+	default:
+		t.Fatal("old channel left open")
+	}
+
+	// the reconnected stream's channel is untouched and still receives broadcasts
+	ms.broadcastToClients(&master_pb.KeepConnectedResponse{
+		VolumeLocation: &master_pb.VolumeLocation{Url: "volume-a:8080"},
+	})
+	select {
+	case message, ok := <-newChan:
+		require.True(t, ok, "reconnected client's channel was closed by the old handler's cleanup")
+		require.NotNil(t, message.GetVolumeLocation())
+	default:
+		t.Fatal("no broadcast reached the reconnected client")
+	}
+
+	// the reconnected handler's own cleanup still removes the registration
+	ms.deleteClient(clientName, newChan)
+	ms.clientChansLock.RLock()
+	_, found := ms.clientChans[clientName]
+	ms.clientChansLock.RUnlock()
+	assert.False(t, found)
+}
+
 // TestBroadcastVolumeLocationsToClients verifies grown volume locations are sent to registered clients.
 func TestBroadcastVolumeLocationsToClients(t *testing.T) {
 	clientChan := make(chan *master_pb.KeepConnectedResponse, 2)