diff --git a/protoc_plugin/CHANGELOG.md b/protoc_plugin/CHANGELOG.md
index 0684291b0..239fb3779 100644
--- a/protoc_plugin/CHANGELOG.md
+++ b/protoc_plugin/CHANGELOG.md
@@ -5,9 +5,13 @@
   fields is now `PbMap` (instead of `Map`). ([#903])
 
   This change requires protobuf-4.0.0.
+* Generated files now export `GeneratedMessageGenericExtensions` from the
+  protobuf library. ([#503], [#907])
 
 [#738]: https://github.com/google/protobuf.dart/issues/738
 [#903]: https://github.com/google/protobuf.dart/pull/903
+[#503]: https://github.com/google/protobuf.dart/issues/503
+[#907]: https://github.com/google/protobuf.dart/pull/907
 
 ## 21.1.2
 
diff --git a/protoc_plugin/lib/indenting_writer.dart b/protoc_plugin/lib/indenting_writer.dart
index 4bdcd32b3..f6b8dae43 100644
--- a/protoc_plugin/lib/indenting_writer.dart
+++ b/protoc_plugin/lib/indenting_writer.dart
@@ -173,14 +173,16 @@ class ImportWriter {
   final Set<String> _dartImports = SplayTreeSet<String>();
   final Set<String> _packageImports = SplayTreeSet<String>();
   final Set<String> _fileImports = SplayTreeSet<String>();
-  final Set<String> _exports = SplayTreeSet<String>();
+  final Set<String> _packageExports = SplayTreeSet<String>();
+  final Set<String> _fileExports = SplayTreeSet<String>();
 
   /// Whether any imports were written.
   bool get hasImports =>
       _dartImports.isNotEmpty ||
       _packageImports.isNotEmpty ||
       _fileImports.isNotEmpty ||
-      _exports.isNotEmpty;
+      _packageExports.isNotEmpty ||
+      _fileExports.isNotEmpty;
 
   /// Add an import with an optional import prefix.
   void addImport(String url, {String? prefix}) {
@@ -196,8 +198,15 @@ class ImportWriter {
   }
 
   /// And an export.
-  void addExport(String url) {
-    _exports.add("export '$url';");
+  void addExport(String url, {List<String> members = const []}) {
+    final directive = members.isNotEmpty
+        ? "export '$url' show ${members.join(', ')};"
+        : "export '$url';";
+    if (url.startsWith('package:')) {
+      _packageExports.add(directive);
+    } else {
+      _fileExports.add(directive);
+    }
   }
 
   /// Return the generated text for the set of imports.
@@ -215,9 +224,13 @@ class ImportWriter {
       if (buf.isNotEmpty) buf.writeln();
       _fileImports.forEach(buf.writeln);
     }
-    if (_exports.isNotEmpty) {
+    if (_packageExports.isNotEmpty) {
+      if (buf.isNotEmpty) buf.writeln();
+      _packageExports.forEach(buf.writeln);
+    }
+    if (_fileExports.isNotEmpty) {
       if (buf.isNotEmpty) buf.writeln();
-      _exports.forEach(buf.writeln);
+      _fileExports.forEach(buf.writeln);
     }
 
     return buf.toString();
diff --git a/protoc_plugin/lib/src/file_generator.dart b/protoc_plugin/lib/src/file_generator.dart
index c1be67312..b14684e81 100644
--- a/protoc_plugin/lib/src/file_generator.dart
+++ b/protoc_plugin/lib/src/file_generator.dart
@@ -341,6 +341,9 @@ class FileGenerator extends ProtobufContainer {
       _addImport(importWriter, config, target, '.pbenum.dart');
     }
 
+    importWriter.addExport(_protobufImportUrl,
+        members: ['GeneratedMessageGenericExtensions']);
+
     for (final publicDependency in descriptor.publicDependency) {
       _addExport(importWriter, config,
           Uri.file(descriptor.dependency[publicDependency]), '.pb.dart');
diff --git a/protoc_plugin/test/goldens/grpc_service.pb b/protoc_plugin/test/goldens/grpc_service.pb
index 3b4a7a456..b7a21b7ce 100644
--- a/protoc_plugin/test/goldens/grpc_service.pb
+++ b/protoc_plugin/test/goldens/grpc_service.pb
@@ -13,6 +13,8 @@ import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
 class Empty extends $pb.GeneratedMessage {
   factory Empty() => create();
   Empty._() : super();
diff --git a/protoc_plugin/test/goldens/header_in_package.pb b/protoc_plugin/test/goldens/header_in_package.pb
index 10a0966ae..14dcfbd6d 100644
--- a/protoc_plugin/test/goldens/header_in_package.pb
+++ b/protoc_plugin/test/goldens/header_in_package.pb
@@ -13,3 +13,5 @@ import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
diff --git a/protoc_plugin/test/goldens/header_with_fixnum.pb b/protoc_plugin/test/goldens/header_with_fixnum.pb
index 04d040a2a..d50ef3dcc 100644
--- a/protoc_plugin/test/goldens/header_with_fixnum.pb
+++ b/protoc_plugin/test/goldens/header_with_fixnum.pb
@@ -14,3 +14,5 @@ import 'dart:core' as $core;
 import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
diff --git a/protoc_plugin/test/goldens/imports.pb b/protoc_plugin/test/goldens/imports.pb
index 5c24303fa..0f8f8913e 100644
--- a/protoc_plugin/test/goldens/imports.pb
+++ b/protoc_plugin/test/goldens/imports.pb
@@ -16,6 +16,8 @@ import 'package:protobuf/protobuf.dart' as $pb;
 import 'package1.pb.dart' as $1;
 import 'package2.pb.dart' as $2;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
 class M extends $pb.GeneratedMessage {
   factory M() => create();
   M._() : super();
diff --git a/protoc_plugin/test/goldens/int64.pb b/protoc_plugin/test/goldens/int64.pb
index a7f914628..047e01216 100644
--- a/protoc_plugin/test/goldens/int64.pb
+++ b/protoc_plugin/test/goldens/int64.pb
@@ -14,6 +14,8 @@ import 'dart:core' as $core;
 import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
 class Int64 extends $pb.GeneratedMessage {
   factory Int64() => create();
   Int64._() : super();
diff --git a/protoc_plugin/test/goldens/oneMessage.pb b/protoc_plugin/test/goldens/oneMessage.pb
index 8ba6be3ad..984bc61b3 100644
--- a/protoc_plugin/test/goldens/oneMessage.pb
+++ b/protoc_plugin/test/goldens/oneMessage.pb
@@ -13,6 +13,8 @@ import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
 class PhoneNumber extends $pb.GeneratedMessage {
   factory PhoneNumber() => create();
   PhoneNumber._() : super();
diff --git a/protoc_plugin/test/goldens/oneMessage.pb.meta b/protoc_plugin/test/goldens/oneMessage.pb.meta
index 1b984ea76..9e1a0e93a 100644
--- a/protoc_plugin/test/goldens/oneMessage.pb.meta
+++ b/protoc_plugin/test/goldens/oneMessage.pb.meta
@@ -2,15 +2,15 @@ annotation: {
   path: 4
   path: 0
   sourceFile: test
-  begin: 445
-  end: 456
+  begin: 526
+  end: 537
 }
 annotation: {
   path: 4
   path: 0
   sourceFile: test
-  begin: 527
-  end: 538
+  begin: 608
+  end: 619
 }
 annotation: {
   path: 4
@@ -18,8 +18,8 @@ annotation: {
   path: 2
   path: 0
   sourceFile: test
-  begin: 2247
-  end: 2253
+  begin: 2328
+  end: 2334
 }
 annotation: {
   path: 4
@@ -27,8 +27,8 @@ annotation: {
   path: 2
   path: 0
   sourceFile: test
-  begin: 2295
-  end: 2301
+  begin: 2376
+  end: 2382
 }
 annotation: {
   path: 4
@@ -36,8 +36,8 @@ annotation: {
   path: 2
   path: 0
   sourceFile: test
-  begin: 2374
-  end: 2383
+  begin: 2455
+  end: 2464
 }
 annotation: {
   path: 4
@@ -45,8 +45,8 @@ annotation: {
   path: 2
   path: 0
   sourceFile: test
-  begin: 2426
-  end: 2437
+  begin: 2507
+  end: 2518
 }
 annotation: {
   path: 4
@@ -54,8 +54,8 @@ annotation: {
   path: 2
   path: 1
   sourceFile: test
-  begin: 2495
-  end: 2499
+  begin: 2576
+  end: 2580
 }
 annotation: {
   path: 4
@@ -63,8 +63,8 @@ annotation: {
   path: 2
   path: 1
   sourceFile: test
-  begin: 2541
-  end: 2545
+  begin: 2622
+  end: 2626
 }
 annotation: {
   path: 4
@@ -72,8 +72,8 @@ annotation: {
   path: 2
   path: 1
   sourceFile: test
-  begin: 2620
-  end: 2627
+  begin: 2701
+  end: 2708
 }
 annotation: {
   path: 4
@@ -81,8 +81,8 @@ annotation: {
   path: 2
   path: 1
   sourceFile: test
-  begin: 2670
-  end: 2679
+  begin: 2751
+  end: 2760
 }
 annotation: {
   path: 4
@@ -90,8 +90,8 @@ annotation: {
   path: 2
   path: 2
   sourceFile: test
-  begin: 2740
-  end: 2744
+  begin: 2821
+  end: 2825
 }
 annotation: {
   path: 4
@@ -99,8 +99,8 @@ annotation: {
   path: 2
   path: 2
   sourceFile: test
-  begin: 2791
-  end: 2795
+  begin: 2872
+  end: 2876
 }
 annotation: {
   path: 4
@@ -108,8 +108,8 @@ annotation: {
   path: 2
   path: 2
   sourceFile: test
-  begin: 2868
-  end: 2875
+  begin: 2949
+  end: 2956
 }
 annotation: {
   path: 4
@@ -117,6 +117,6 @@ annotation: {
   path: 2
   path: 2
   sourceFile: test
-  begin: 2918
-  end: 2927
+  begin: 2999
+  end: 3008
 }
diff --git a/protoc_plugin/test/goldens/service.pb b/protoc_plugin/test/goldens/service.pb
index aeeafadaf..706e352af 100644
--- a/protoc_plugin/test/goldens/service.pb
+++ b/protoc_plugin/test/goldens/service.pb
@@ -14,6 +14,8 @@ import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
 class Empty extends $pb.GeneratedMessage {
   factory Empty() => create();
   Empty._() : super();
diff --git a/protoc_plugin/test/goldens/topLevelEnum.pb b/protoc_plugin/test/goldens/topLevelEnum.pb
index 09c5d230a..9a8ed6010 100644
--- a/protoc_plugin/test/goldens/topLevelEnum.pb
+++ b/protoc_plugin/test/goldens/topLevelEnum.pb
@@ -11,5 +11,7 @@
 
 import 'dart:core' as $core;
 
+export 'package:protobuf/protobuf.dart' show GeneratedMessageGenericExtensions;
+
 export 'test.pbenum.dart';
 
diff --git a/protoc_plugin/test/oneof_test.dart b/protoc_plugin/test/oneof_test.dart
index 5223c85ed..ccbf8a9d7 100644
--- a/protoc_plugin/test/oneof_test.dart
+++ b/protoc_plugin/test/oneof_test.dart
@@ -2,7 +2,6 @@
 // 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.
 
-import 'package:protobuf/protobuf.dart';
 import 'package:test/test.dart';
 
 import '../out/protos/oneof.pb.dart';