diff --git a/server/cluster_worker_test.go b/server/cluster_worker_test.go
index f244a235df1..381fe9b009c 100644
--- a/server/cluster_worker_test.go
+++ b/server/cluster_worker_test.go
@@ -411,6 +411,27 @@ func (s *testClusterWorkerSuite) checkSearchRegions(cluster *RaftCluster, keys .
 	}
 }
 
+func (s *testClusterWorkerSuite) TestEmptyRegionKey(c *C) {
+	cluster := s.svr.GetRaftCluster()
+	c.Assert(cluster, NotNil)
+	r1, _ := cluster.GetRegionByKey([]byte("a"))
+	// Bootstrap region is ["", "").
+	c.Assert(r1.StartKey, HasLen, 0)
+	c.Assert(r1.EndKey, HasLen, 0)
+	// For the region key, nil is the same as "".
+	r1.StartKey, r1.EndKey = nil, nil
+	req := &pdpb.AskSplitRequest{
+		Header: newRequestHeader(s.clusterID),
+		Region: r1,
+	}
+	_, err := s.grpcPDClient.AskSplit(context.Background(), req)
+	c.Assert(err, IsNil)
+	// Without region will get an error.
+	req.Region = nil
+	_, err = s.grpcPDClient.AskSplit(context.Background(), req)
+	c.Assert(err, NotNil)
+}
+
 func (s *testClusterWorkerSuite) TestHeartbeatSplit(c *C) {
 	cluster := s.svr.GetRaftCluster()
 	c.Assert(cluster, NotNil)
diff --git a/server/grpc_service.go b/server/grpc_service.go
index d25999b113c..ac574d4f55b 100644
--- a/server/grpc_service.go
+++ b/server/grpc_service.go
@@ -389,8 +389,8 @@ func (s *Server) AskSplit(ctx context.Context, request *pdpb.AskSplitRequest) (*
 	if cluster == nil {
 		return &pdpb.AskSplitResponse{Header: s.notBootstrappedHeader()}, nil
 	}
-	if request.GetRegion().GetStartKey() == nil {
-		return nil, errors.New("missing region start key for split")
+	if request.GetRegion() == nil {
+		return nil, errors.New("missing region for split")
 	}
 	req := &pdpb.AskSplitRequest{
 		Region: request.Region,