diff --git a/pkg/file/file_mgr.go b/pkg/file/file_mgr.go
index b18efa9..c5c4df1 100644
--- a/pkg/file/file_mgr.go
+++ b/pkg/file/file_mgr.go
@@ -19,12 +19,15 @@ type FileMgrImpl struct {
 
 func NewFileMgr(dbDir string, blockSize int) *FileMgrImpl {
 	_, err := os.Stat(dbDir)
-	fileExists := !os.IsNotExist(err)
+	notExists := os.IsNotExist(err)
+	if notExists {
+		_ = os.MkdirAll(dbDir, 0755)
+	}
 
 	return &FileMgrImpl{
 		dbDir:     dbDir,
 		blockSize: blockSize,
-		isNew:     fileExists,
+		isNew:     notExists,
 		openFiles: make(map[string]*os.File),
 	}
 }
diff --git a/pkg/file/file_mgr_test.go b/pkg/file/file_mgr_test.go
index 43b55d5..17c3ca3 100644
--- a/pkg/file/file_mgr_test.go
+++ b/pkg/file/file_mgr_test.go
@@ -5,28 +5,30 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/kj455/simple-db/pkg/testutil"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestNewFileMgr(t *testing.T) {
 	t.Parallel()
-	const (
-		dbDir     = "test"
-		blockSize = 4096
-	)
+	const blockSize = 4096
 	t.Run("new", func(t *testing.T) {
 		t.Parallel()
+		dbDir := "test_new_file_mgr_new"
 		mgr := NewFileMgr(dbDir, blockSize)
+		t.Cleanup(func() {
+			os.RemoveAll(dbDir)
+		})
 		assert.Equal(t, dbDir, mgr.dbDir)
 		assert.Equal(t, blockSize, mgr.blockSize)
-		assert.False(t, mgr.isNew)
+		assert.True(t, mgr.isNew)
 	})
 	t.Run("existing", func(t *testing.T) {
 		t.Parallel()
-		os.Mkdir(dbDir, 0755)
-		defer os.RemoveAll(dbDir)
-		mgr := NewFileMgr(dbDir, blockSize)
-		assert.True(t, mgr.isNew)
+		dir, cleanup := testutil.SetupDir("test_new_file_mgr_existing")
+		t.Cleanup(cleanup)
+		mgr := NewFileMgr(dir, blockSize)
+		assert.False(t, mgr.isNew)
 	})
 }