diff --git a/internal/bundb/group.go b/internal/bundb/group.go
index 7bea9fd..a7efdf4 100644
--- a/internal/bundb/group.go
+++ b/internal/bundb/group.go
@@ -86,6 +86,10 @@ func (g *Group) List(ctx context.Context, params domain.ListGroupsParams) ([]dom
 }
 
 func (g *Group) Delete(ctx context.Context, id, serverID string) error {
+	if _, err := uuid.Parse(id); err != nil {
+		return domain.GroupNotFoundError{ID: id}
+	}
+
 	res, err := g.db.NewDelete().
 		Model(&model.Group{}).
 		Returning("NULL").
diff --git a/internal/bundb/group_test.go b/internal/bundb/group_test.go
index 0d54404..bff391c 100644
--- a/internal/bundb/group_test.go
+++ b/internal/bundb/group_test.go
@@ -210,6 +210,13 @@ func TestGroup_Delete(t *testing.T) {
 		assert.Len(t, groups, 0)
 	})
 
+	t.Run("ERR: invalid UUID", func(t *testing.T) {
+		t.Parallel()
+
+		id := "12345"
+		assert.ErrorIs(t, repo.Delete(context.Background(), id, ""), domain.GroupNotFoundError{ID: id})
+	})
+
 	t.Run("ERR: group not found (unknown ID)", func(t *testing.T) {
 		t.Parallel()