diff --git a/lib/jmdict/objects.dart b/lib/jmdict/objects.dart
index 2271d59..9604507 100644
--- a/lib/jmdict/objects.dart
+++ b/lib/jmdict/objects.dart
@@ -1,7 +1,7 @@
 import 'package:jadb/objects.dart';
 
 
-class TableNames {
+abstract class TableNames {
   static const String entry = 'JMdict_Entry';
   static const String entryByKana = 'JMdict_EntryByKana';
   static const String entryByEnglish = 'JMdict_EntryByEnglish';
diff --git a/lib/kanjidic/objects.dart b/lib/kanjidic/objects.dart
index e700b46..4e52465 100644
--- a/lib/kanjidic/objects.dart
+++ b/lib/kanjidic/objects.dart
@@ -1,6 +1,6 @@
 import 'package:jadb/objects.dart';
 
-class TableNames {
+abstract class TableNames {
   static const String character = 'KANJIDIC_Character';
   static const String radicalName = 'KANJIDIC_RadicalName';
   static const String codepoint = 'KANJIDIC_Codepoint';