diff --git a/plan/storage/memory/localid.go b/plan/storage/memory/localid.go
index 838e80a..ece7ba1 100644
--- a/plan/storage/memory/localid.go
+++ b/plan/storage/memory/localid.go
@@ -38,9 +38,6 @@ func (ml *LocalID) Find(id string) (int, error) {
 }
 
 func (ml *LocalID) FindOrNext(id string) (int, error) {
-	ml.mutex.Lock()
-	defer ml.mutex.Unlock()
-
 	lid, err := ml.Find(id)
 	switch {
 	case errors.Is(err, storage.ErrNotFound):
diff --git a/plan/storage/memory/localid_test.go b/plan/storage/memory/localid_test.go
index f750e30..eddaf6f 100644
--- a/plan/storage/memory/localid_test.go
+++ b/plan/storage/memory/localid_test.go
@@ -45,6 +45,14 @@ func TestLocalID(t *testing.T) {
 	if actLid != 1 {
 		t.Errorf("exp 1, git %v", actLid)
 	}
+	t.Log("retrieve unknown")
+	actLid, actErr = repo.FindOrNext("new")
+	if actErr != nil {
+		t.Errorf("exp nil, got %v", actErr)
+	}
+	if actLid != 2 {
+		t.Errorf("exp 2, got %v", actLid)
+	}
 
 	actIDs, actErr = repo.FindAll()
 	if actErr != nil {