diff --git a/cayley_test.go b/cayley_test.go
index 1f2685c..75ebd00 100644
--- a/cayley_test.go
+++ b/cayley_test.go
@@ -392,6 +392,9 @@ func prepare(t testing.TB) {
 		}
 	case "mongo":
 		cfg.DatabasePath = "localhost:27017"
+		cfg.DatabaseOptions = map[string]interface{}{
+			"database_name": "cayley_test", // provide a default test database
+		}
 	default:
 		t.Fatalf("Untestable backend store %s", *backend)
 	}
diff --git a/graph/mongo/quadstore.go b/graph/mongo/quadstore.go
index f2bcf51..25c7758 100644
--- a/graph/mongo/quadstore.go
+++ b/graph/mongo/quadstore.go
@@ -305,8 +305,9 @@ func (qs *QuadStore) NameOf(v graph.Value) string {
 	err := qs.db.C("nodes").FindId(v.(string)).One(&node)
 	if err != nil {
 		glog.Errorf("Error: Couldn't retrieve node %s %v", v, err)
+	} else if node.ID != "" && node.Name != "" {
+		qs.ids.Put(v.(string), node.Name)
 	}
-	qs.ids.Put(v.(string), node.Name)
 	return node.Name
 }