diff --git a/pkg/nnbd_migration/lib/src/transitional_api.dart b/pkg/nnbd_migration/lib/src/transitional_api.dart
index 9c2c5eb..f9045c1 100644
--- a/pkg/nnbd_migration/lib/src/transitional_api.dart
+++ b/pkg/nnbd_migration/lib/src/transitional_api.dart
@@ -114,8 +114,7 @@
   NullabilityMigration(NullabilityMigrationListener /*?*/ listener)
       : this._(listener, NullabilityGraph());
 
-  NullabilityMigration._(this.listener, this._graph)
-      : _variables = Variables(_graph);
+  NullabilityMigration._(this.listener, this._graph) : _variables = Variables();
 
   Map<Source, List<PotentialModification>> finish() {
     _graph.propagate();
@@ -205,10 +204,6 @@
 
   final _potentialModifications = <Source, List<PotentialModification>>{};
 
-  final NullabilityGraph _graph;
-
-  Variables(this._graph);
-
   @override
   DecoratedType decoratedElementType(Element element, {bool create: false}) =>
       _decoratedElementTypes[element] ??= create
diff --git a/pkg/nnbd_migration/test/migration_visitor_test.dart b/pkg/nnbd_migration/test/migration_visitor_test.dart
index 23b759b..87af31d 100644
--- a/pkg/nnbd_migration/test/migration_visitor_test.dart
+++ b/pkg/nnbd_migration/test/migration_visitor_test.dart
@@ -1137,7 +1137,7 @@
 
   MigrationVisitorTestBase() : this._(NullabilityGraph());
 
-  MigrationVisitorTestBase._(this.graph) : _variables = _Variables(graph);
+  MigrationVisitorTestBase._(this.graph) : _variables = _Variables();
 
   NullabilityNode get always => NullabilityNode.always;
 
@@ -1388,8 +1388,6 @@
 
   final _possiblyOptional = <DefaultFormalParameter, NullabilityNode>{};
 
-  _Variables(NullabilityGraph graph) : super(graph);
-
   /// Gets the [ExpressionChecks] associated with the given [expression].
   ExpressionChecks checkExpression(Expression expression) =>
       _expressionChecks[_normalizeExpression(expression)];