diff --git a/pkg/front_end/lib/src/fasta/source/outline_builder.dart b/pkg/front_end/lib/src/fasta/source/outline_builder.dart
index 02319db..5b1f67f 100644
--- a/pkg/front_end/lib/src/fasta/source/outline_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/outline_builder.dart
@@ -475,6 +475,16 @@
   }
 
   @override
+  void beginClassOrMixinBody(Token token) {
+    debugEvent("beginClassOrMixinBody");
+    // Resolve unresolved types from the class header (i.e., superclass, mixins,
+    // and implemented types) before adding members from the class body which
+    // should not shadow these unresolved types.
+    library.currentDeclaration
+        .resolveTypes(library.currentDeclaration.typeVariables, library);
+  }
+
+  @override
   void beginNamedMixinApplication(
       Token begin, Token abstractToken, Token name) {
     debugEvent("beginNamedMixinApplication");
diff --git a/tests/language_2/issue34870_test.dart b/tests/language_2/issue34870_test.dart
new file mode 100644
index 0000000..750048d
--- /dev/null
+++ b/tests/language_2/issue34870_test.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test: superclass is not shadowed by class members.
+
+class A extends B {
+  B() {}
+}
+
+class B {}
+
+main() {}