diff --git a/moor/lib/src/runtime/query_builder/statements/select/select.dart b/moor/lib/src/runtime/query_builder/statements/select/select.dart
index 3dbfe7fa..b92a5a78 100644
--- a/moor/lib/src/runtime/query_builder/statements/select/select.dart
+++ b/moor/lib/src/runtime/query_builder/statements/select/select.dart
@@ -5,7 +5,9 @@ part of '../../query_builder.dart';
 typedef OrderClauseGenerator<T> = OrderingTerm Function(T tbl);
 
 /// The abstract base class for all select statements in the moor api.
-@internal
+///
+/// Users are not allowed to extend, implement or mix-in this class.
+@sealed
 abstract class BaseSelectStatement extends Component {
   int get _returnedColumnCount;
 }