diff --git a/test/sharding/tree_concurrency_test.go b/test/sharding/tree_concurrency_test.go
index 30796c6c8..55c7e9f4f 100644
--- a/test/sharding/tree_concurrency_test.go
+++ b/test/sharding/tree_concurrency_test.go
@@ -23,6 +23,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/yorkie-team/yorkie/client"
 
 	"github.com/yorkie-team/yorkie/pkg/document"
 	"github.com/yorkie-team/yorkie/pkg/document/json"