diff --git a/client/client.go b/client/client.go
index a9dc3971944..ed021b95ae4 100644
--- a/client/client.go
+++ b/client/client.go
@@ -321,7 +321,9 @@ func (k *serviceModeKeeper) close() {
 	defer k.Unlock()
 	switch k.serviceMode {
 	case pdpb.ServiceMode_API_SVC_MODE:
-		k.tsoSvcDiscovery.Close()
+		if k.tsoSvcDiscovery != nil {
+			k.tsoSvcDiscovery.Close()
+		}
 		fallthrough
 	case pdpb.ServiceMode_PD_SVC_MODE:
 		if k.tsoClient != nil {
diff --git a/tests/integrations/mcs/tso/server_test.go b/tests/integrations/mcs/tso/server_test.go
index 56a8a96092c..cc11b1ba46d 100644
--- a/tests/integrations/mcs/tso/server_test.go
+++ b/tests/integrations/mcs/tso/server_test.go
@@ -323,6 +323,7 @@ func TestForwardTSOWhenPrimaryChanged(t *testing.T) {
 
 func TestResignTSOPrimaryForward(t *testing.T) {
 	re := require.New(t)
+	re.NoError(failpoint.Enable("github.com/tikv/pd/client/fastUpdateServiceMode", `return(true)`))
 	suite := NewAPIServerForward(re)
 	defer suite.ShutDown()
 	// TODO: test random kill primary with 3 nodes
@@ -345,6 +346,7 @@ func TestResignTSOPrimaryForward(t *testing.T) {
 		re.NoError(err)
 		suite.checkAvailableTSO(re, true)
 	}
+	re.NoError(failpoint.Disable("github.com/tikv/pd/client/fastUpdateServiceMode"))
 }
 
 func TestResignAPIPrimaryForward(t *testing.T) {