diff --git a/protobuf/lib/src/protobuf/mixins/well_known.dart b/protobuf/lib/src/protobuf/mixins/well_known.dart
new file mode 100644
index 0000000..6f8c647
--- /dev/null
+++ b/protobuf/lib/src/protobuf/mixins/well_known.dart
@@ -0,0 +1,68 @@
+import 'package:fixnum/fixnum.dart';
+
+import '../../../protobuf.dart';
+
+abstract class AnyMixin {
+  String get typeUrl;
+  set typeUrl(String value);
+  List<int> get value;
+  set value(List<int> value);
+
+  /// Returns `true` if the encoded message matches the type of [instance].
+  ///
+  /// Can be used with a default instance:
+  /// `any.canUnpackInto(Message.getDefault())`
+  bool canUnpackInto(GeneratedMessage instance) {
+    return canUnpackIntoHelper(instance, typeUrl);
+  }
+
+  /// Unpacks the message in [value] into [instance].
+  ///
+  /// Throws a [InvalidProtocolBufferException] if [typeUrl] does not correspond
+  /// to the type of [instance].
+  ///
+  /// A typical usage would be `any.unpackInto(Message())`.
+  ///
+  /// Returns [instance].
+  T unpackInto<T extends GeneratedMessage>(T instance,
+      {ExtensionRegistry extensionRegistry = ExtensionRegistry.EMPTY}) {
+    unpackIntoHelper(value, instance, typeUrl,
+        extensionRegistry: extensionRegistry);
+    return instance;
+  }
+
+  /// Updates [target] to be the packed representation of [message].
+  ///
+  /// The [typeUrl] will be [typeUrlPrefix]/`fullName` where `fullName` is
+  /// the fully qualified name of the type of [message].
+  static void packIntoAny(AnyMixin target, GeneratedMessage message,
+      {String typeUrlPrefix = 'type.googleapis.com'}) {
+    target.value = message.writeToBuffer();
+    target.typeUrl = '${typeUrlPrefix}/${message.info_.qualifiedMessageName}';
+  }
+}
+
+abstract class TimestampMixin {
+  Int64 get seconds;
+  set seconds(Int64 value);
+
+  int get nanos;
+  set nanos(int value);
+
+  /// Converts an instance to [DateTime].
+  ///
+  /// The result is in UTC time zone and has microsecond precision, as
+  /// [DateTime] does not support nanosecond precision.
+  DateTime toDateTime() => new DateTime.fromMicrosecondsSinceEpoch(
+      seconds.toInt() * Duration.microsecondsPerSecond + nanos ~/ 1000,
+      isUtc: true);
+
+  /// Updates [target] to be the time at [datetime].
+  ///
+  /// Time zone information will not be preserved.
+  static void setFromDateTime(TimestampMixin target, DateTime dateTime) {
+    int micros = dateTime.microsecondsSinceEpoch;
+    target.seconds = Int64(micros ~/ Duration.microsecondsPerSecond);
+    target.nanos = (micros % Duration.microsecondsPerSecond).toInt() * 1000;
+  }
+}
diff --git a/protoc_plugin/CHANGELOG.md b/protoc_plugin/CHANGELOG.md
index a99c0db..b960658 100644
--- a/protoc_plugin/CHANGELOG.md
+++ b/protoc_plugin/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 18.0.0
 
 * Breaking: Generates code that requires at least `protobuf` 0.14.0.
+
 * Generate the non-camel-case name of fields when it cannot be derived from the json name.
 
 * Breaking: Use the correct proto3 Json CamelCase names for the string representation of field
@@ -20,6 +21,9 @@
   `GeneratedMessage.toString()` also uses the string representation. It will now print the
   json-name.
 
+* Well-known types (for now only `google.protobuf.Any` and `google.protobuf.Timestamp`) now uses a
+  mixin to add special handling code instead of hardcoding it in the compiler.
+
 ## 17.0.5
 
 * Remove unnecessary cast from generated grpc stubs. 
diff --git a/protoc_plugin/lib/file_generator.dart b/protoc_plugin/lib/file_generator.dart
index 8ce17a1..c1b355c 100644
--- a/protoc_plugin/lib/file_generator.dart
+++ b/protoc_plugin/lib/file_generator.dart
@@ -6,15 +6,16 @@
 
 final _dartIdentifier = RegExp(r'^\w+$');
 final _formatter = DartFormatter();
-final String _protobufImportPrefix = r'$pb';
-final String _asyncImportPrefix = r'$async';
+const String _protobufImportPrefix = r'$pb';
+const String _asyncImportPrefix = r'$async';
 const String _coreImportPrefix = r'$core';
-final String _grpcImportPrefix = r'$grpc';
-final String _protobufImport =
+const String _grpcImportPrefix = r'$grpc';
+const String _mixinImportPrefix = r'$mixin';
+const String _protobufImport =
     "import 'package:protobuf/protobuf.dart' as $_protobufImportPrefix;";
-final String _asyncImport = "import 'dart:async' as $_asyncImportPrefix;";
-final String _coreImport = "import 'dart:core' as $_coreImportPrefix";
-final String _grpcImport =
+const String _asyncImport = "import 'dart:async' as $_asyncImportPrefix;";
+const String _coreImport = "import 'dart:core' as $_coreImportPrefix;";
+const String _grpcImport =
     "import 'package:grpc/service_api.dart' as $_grpcImportPrefix;";
 
 /// Generates the Dart output files for one .proto input file.
@@ -285,8 +286,7 @@
       out.println(_asyncImport);
     }
 
-    out.println('$_coreImport show '
-        'bool, Deprecated, double, int, List, Map, override, pragma, String;');
+    out.println(_coreImport);
     out.println();
 
     if (_needsFixnumImport) {
@@ -298,12 +298,9 @@
       out.println();
     }
 
-    var mixinImports = findMixinsToImport();
-    var importNames = mixinImports.keys.toList();
-    importNames.sort();
-    for (var imp in importNames) {
-      var symbols = mixinImports[imp];
-      out.println("import '${imp}' show ${symbols.join(', ')};");
+    final mixinImports = findMixinImports();
+    for (var libraryUri in mixinImports) {
+      out.println("import '$libraryUri' as $_mixinImportPrefix;");
     }
     if (mixinImports.isNotEmpty) out.println();
 
@@ -322,8 +319,6 @@
     }
     if (enumImports.isNotEmpty) out.println();
 
-    _writeWellKnownImports(out);
-
     // Export enums in main file for backward compatibility.
     if (enumCount > 0) {
       Uri resolvedImport =
@@ -333,17 +328,6 @@
     }
   }
 
-  void _writeWellKnownImports(IndentingWriter out) {
-    for (final message in messageGenerators) {
-      final importStatements =
-          wellKnownTypeForFullName(message.fullName)?.extraImports ??
-              <String>[];
-      for (String importStatement in importStatements) {
-        out.println(importStatement);
-      }
-    }
-  }
-
   bool get _needsFixnumImport {
     for (var m in messageGenerators) {
       if (m.needsFixnumImport) return true;
@@ -376,29 +360,18 @@
     imports.remove(this);
   }
 
-  /// Returns a map from import names to the Dart symbols to be imported.
-  Map<String, List<String>> findMixinsToImport() {
+  /// Returns a sorted list of imports needed to support all mixins.
+  List<String> findMixinImports() {
     var mixins = Set<PbMixin>();
     for (MessageGenerator m in messageGenerators) {
       m.addMixinsTo(mixins);
     }
 
-    var imports = <String, List<String>>{};
-    for (var m in mixins) {
-      var imp = m.importFrom;
-      List<String> symbols = imports[imp];
-      if (symbols == null) {
-        symbols = [];
-        imports[imp] = symbols;
-      }
-      symbols.add(m.name);
-    }
-
-    for (var imp in imports.keys) {
-      imports[imp].sort();
-    }
-
-    return imports;
+    return mixins
+        .map((mixin) => mixin.importFrom)
+        .toSet()
+        .toList(growable: false)
+          ..sort();
   }
 
   /// Returns the contents of the .pbenum.dart file for this .proto file.
@@ -413,7 +386,7 @@
       // Make sure any other symbols in dart:core don't cause name conflicts
       // with enums that have the same name.
       out.println("// ignore_for_file: UNDEFINED_SHOWN_NAME,UNUSED_SHOWN_NAME");
-      out.println("$_coreImport show int, dynamic, String, List, Map;");
+      out.println(_coreImport);
       out.println(_protobufImport);
       out.println();
     }
@@ -450,7 +423,7 @@
       out.println();
       out.println(_protobufImport);
       out.println();
-      out.println("$_coreImport show String, Map, ArgumentError, dynamic;");
+      out.println(_coreImport);
     }
 
     // Import .pb.dart files needed for requests and responses.
@@ -489,7 +462,7 @@
 
     out.println(_asyncImport);
     out.println();
-    out.println("$_coreImport show int, String, List;\n");
+    out.println(_coreImport);
     out.println();
     out.println(_grpcImport);
 
diff --git a/protoc_plugin/lib/message_generator.dart b/protoc_plugin/lib/message_generator.dart
index 4eedd5f..e09566b 100644
--- a/protoc_plugin/lib/message_generator.dart
+++ b/protoc_plugin/lib/message_generator.dart
@@ -22,25 +22,6 @@
 }
 
 class MessageGenerator extends ProtobufContainer {
-  /// Returns the mixin for this message, or null if none.
-  ///
-  /// First searches [declaredMixins], then internal mixins declared by
-  /// [findMixin].
-  static PbMixin _getMixin(DescriptorProto desc, FileDescriptorProto file,
-      Map<String, PbMixin> declaredMixins, PbMixin defaultMixin) {
-    if (!desc.hasOptions() || !desc.options.hasExtension(Dart_options.mixin)) {
-      return defaultMixin;
-    }
-
-    String name = desc.options.getExtension(Dart_options.mixin);
-    if (name.isEmpty) return null; // don't use any mixins (override default)
-    var mixin = declaredMixins[name] ?? findMixin(name);
-    if (mixin == null) {
-      throw '${desc.name} in ${file.name}: mixin "$name" not found';
-    }
-    return mixin;
-  }
-
   /// The name of the Dart class to generate.
   final String classname;
 
@@ -66,7 +47,7 @@
   String get messageName =>
       fullName.substring(package.isEmpty ? 0 : package.length + 1);
 
-  final PbMixin mixin;
+  PbMixin mixin;
 
   final ProtobufContainer _parent;
   final DescriptorProto _descriptor;
@@ -107,10 +88,9 @@
         fullName = parent.fullName == ''
             ? descriptor.name
             : '${parent.fullName}.${descriptor.name}',
-        mixin = _getMixin(descriptor, parent.fileGen.descriptor, declaredMixins,
-            defaultMixin),
         _oneofFields =
             List.generate(descriptor.oneofDecl.length, (int index) => []) {
+    mixin = _getMixin(declaredMixins, defaultMixin);
     for (var i = 0; i < _descriptor.enumType.length; i++) {
       EnumDescriptorProto e = _descriptor.enumType[i];
       _enumGenerators.add(EnumGenerator.nested(e, this, _usedTopLevelNames, i));
@@ -303,7 +283,8 @@
 
     var mixinClause = '';
     if (mixin != null) {
-      var mixinNames = mixin.findMixinsToApply().map((m) => m.name);
+      var mixinNames =
+          mixin.findMixinsToApply().map((m) => '$_mixinImportPrefix.${m.name}');
       mixinClause = ' with ${mixinNames.join(", ")}';
     }
 
@@ -387,7 +368,7 @@
           'static ${classname} getDefault() => _defaultInstance ??= create()..freeze();');
       out.println('static ${classname} _defaultInstance;');
       generateFieldsAccessorsMutators(out);
-      wellKnownTypeForFullName(fullName)?.generateMethods(out);
+      mixin?.injectHelpers(out);
     });
     out.println();
   }
@@ -621,4 +602,25 @@
       e.generateConstants(out);
     }
   }
+
+  /// Returns the mixin for this message, or null if none.
+  ///
+  /// First searches [wellKnownMixins], then [declaredMixins],
+  /// then internal mixins declared by [findMixin].
+  PbMixin _getMixin(Map<String, PbMixin> declaredMixins, PbMixin defaultMixin) {
+    PbMixin wellKnownMixin = wellKnownMixinForFullName(fullName);
+    if (wellKnownMixin != null) return wellKnownMixin;
+    if (!_descriptor.hasOptions() ||
+        !_descriptor.options.hasExtension(Dart_options.mixin)) {
+      return defaultMixin;
+    }
+
+    String name = _descriptor.options.getExtension(Dart_options.mixin);
+    if (name.isEmpty) return null; // don't use any mixins (override default)
+    var mixin = declaredMixins[name] ?? findMixin(name);
+    if (mixin == null) {
+      throw '${_descriptor.name} in ${_parent.fileGen.descriptor.name}: mixin "$name" not found';
+    }
+    return mixin;
+  }
 }
diff --git a/protobuf/lib/mixins_meta.dart b/protoc_plugin/lib/mixins.dart
similarity index 78%
rename from protobuf/lib/mixins_meta.dart
rename to protoc_plugin/lib/mixins.dart
index cfef320..06b9dc6 100644
--- a/protobuf/lib/mixins_meta.dart
+++ b/protoc_plugin/lib/mixins.dart
@@ -4,16 +4,15 @@
 
 /// Provides metadata about mixins to dart-protoc-plugin.
 /// (Experimental API; subject to change.)
-library protobuf.mixins.meta;
+import 'indenting_writer.dart';
 
-/// Entry point called by dart-protoc-plugin.
+/// Finds [name] in the exported mixins.
 PbMixin findMixin(String name) {
-  for (var m in _exportedMixins) {
-    if (m.name == name) {
-      return m;
-    }
-  }
-  return null; // not found
+  const _exportedMixins = {
+    'PbMapMixin': _pbMapMixin,
+    'PbEventMixin': _pbEventMixin,
+  };
+  return _exportedMixins[name];
 }
 
 /// PbMixin contains metadata needed by dart-protoc-plugin to apply a mixin.
@@ -35,7 +34,13 @@
   /// May be null if the mixin doesn't reserve any new names.
   final List<String> reservedNames;
 
-  const PbMixin(this.name, {this.importFrom, this.parent, this.reservedNames});
+  ///  Code to inject into the class using the mixin.
+  ///
+  /// Typically used for static helpers since you cannot mix in static members.
+  final List<String> injectedHelpers;
+
+  const PbMixin(this.name,
+      {this.importFrom, this.parent, this.reservedNames, this.injectedHelpers});
 
   /// Returns the mixin and its ancestors, in the order they should be applied.
   Iterable<PbMixin> findMixinsToApply() {
@@ -57,10 +62,13 @@
     }
     return names;
   }
-}
 
-/// The mixins that findMixin() can return.
-final _exportedMixins = [_pbMapMixin, _pbEventMixin];
+  void injectHelpers(IndentingWriter out) {
+    if (injectedHelpers != null && injectedHelpers.isNotEmpty) {
+      out.println(injectedHelpers.join('\n'));
+    }
+  }
+}
 
 const _pbMapMixin = PbMixin("PbMapMixin",
     importFrom: "package:protobuf/src/protobuf/mixins/map_mixin.dart",
diff --git a/protoc_plugin/lib/protoc.dart b/protoc_plugin/lib/protoc.dart
index b354cec..67f35f4 100644
--- a/protoc_plugin/lib/protoc.dart
+++ b/protoc_plugin/lib/protoc.dart
@@ -4,7 +4,6 @@
 import 'dart:io';
 
 import 'package:dart_style/dart_style.dart';
-import 'package:protobuf/mixins_meta.dart';
 import 'package:protobuf/protobuf.dart';
 import 'package:path/path.dart' as path;
 
@@ -15,6 +14,7 @@
 import 'const_generator.dart' show writeJsonConst;
 import 'indenting_writer.dart';
 import 'names.dart';
+import 'mixins.dart';
 
 part 'base_type.dart';
 part 'client_generator.dart';
diff --git a/protoc_plugin/lib/well_known_types.dart b/protoc_plugin/lib/well_known_types.dart
index a403c3e..9ac1829 100644
--- a/protoc_plugin/lib/well_known_types.dart
+++ b/protoc_plugin/lib/well_known_types.dart
@@ -4,91 +4,37 @@
 
 part of protoc;
 
-abstract class WellKnownType {
-  const WellKnownType();
+PbMixin wellKnownMixinForFullName(String qualifiedName) =>
+    _wellKnownMixins[qualifiedName];
 
-  List<String> get extraImports => <String>[];
-
-  void generateMethods(IndentingWriter out);
-}
-
-class _Any extends WellKnownType {
-  const _Any();
-
-  /// Generates methods for the Any message class for packing and unpacking
-  /// values.
-  @override
-  void generateMethods(IndentingWriter out) {
-    out.println('''
-  /// Unpacks the message in [value] into [instance].
-  ///
-  /// Throws a [InvalidProtocolBufferException] if [typeUrl] does not correspond
-  /// to the type of [instance].
-  ///
-  /// A typical usage would be `any.unpackInto(Message())`.
-  ///
-  /// Returns [instance].
-  T unpackInto<T extends $_protobufImportPrefix.GeneratedMessage>(T instance,
-      {$_protobufImportPrefix.ExtensionRegistry extensionRegistry = $_protobufImportPrefix.ExtensionRegistry.EMPTY}) {
-    $_protobufImportPrefix.unpackIntoHelper(value, instance, typeUrl,
-        extensionRegistry: extensionRegistry);
-    return instance;
-  }
-
-  /// Returns `true` if the encoded message matches the type of [instance].
-  ///
-  /// Can be used with a default instance:
-  /// `any.canUnpackInto(Message.getDefault())`
-  $_coreImportPrefix.bool canUnpackInto($_protobufImportPrefix.GeneratedMessage instance) {
-    return $_protobufImportPrefix.canUnpackIntoHelper(instance, typeUrl);
-  }
-
-  /// Creates a new [Any] encoding [message].
-  ///
-  /// The [typeUrl] will be [typeUrlPrefix]/`fullName` where `fullName` is
-  /// the fully qualified name of the type of [message].
-  static Any pack($_protobufImportPrefix.GeneratedMessage message,
-      {$_coreImportPrefix.String typeUrlPrefix = 'type.googleapis.com'}) {
-    return Any()
-      ..value = message.writeToBuffer()
-      ..typeUrl = '\${typeUrlPrefix}/\${message.info_.qualifiedMessageName}';
-  }''');
-  }
-}
-
-class _Timestamp extends WellKnownType {
-  const _Timestamp();
-
-  List<String> get extraImports =>
-      [r"import 'dart:core' as $core show DateTime, Duration;"];
-
-  @override
-  void generateMethods(IndentingWriter out) {
-    out.println('''
-  /// Converts an instance to [DateTime].
-  ///
-  /// The result is in UTC time zone and has microsecond precision, as
-  /// [DateTime] does not support nanosecond precision.
-  $_coreImportPrefix.DateTime toDateTime() => $_coreImportPrefix.DateTime.fromMicrosecondsSinceEpoch(
-      seconds.toInt() * $_coreImportPrefix.Duration.microsecondsPerSecond + nanos ~/ 1000,
-      isUtc: true);
-
-  /// Creates a new instance from [dateTime].
-  ///
-  /// Time zone information will not be preserved.
-  static Timestamp fromDateTime($_coreImportPrefix.DateTime dateTime) {
-    $_coreImportPrefix.int micros = dateTime.microsecondsSinceEpoch;
-    return Timestamp()
-      ..seconds = Int64(micros ~/ $_coreImportPrefix.Duration.microsecondsPerSecond)
-      ..nanos = (micros % $_coreImportPrefix.Duration.microsecondsPerSecond).toInt() * 1000;
-  }''');
-  }
-}
-
-const _wellKnownTypes = {
-  'google.protobuf.Any': _Any(),
-  'google.protobuf.Timestamp': _Timestamp(),
+const _wellKnownMixins = {
+  'google.protobuf.Any': PbMixin('AnyMixin',
+      importFrom: 'package:protobuf/src/protobuf/mixins/well_known.dart',
+      injectedHelpers: [
+        '''
+/// Creates a new [Any] encoding [message].
+///
+/// The [typeUrl] will be [typeUrlPrefix]/`fullName` where `fullName` is
+/// the fully qualified name of the type of [message].
+static Any pack($_protobufImportPrefix.GeneratedMessage message,
+{$_coreImportPrefix.String typeUrlPrefix = 'type.googleapis.com'}) {
+  final result = create();
+  $_mixinImportPrefix.AnyMixin.packIntoAny(result, message,
+      typeUrlPrefix: typeUrlPrefix);
+  return result;
+}'''
+      ]),
+  'google.protobuf.Timestamp': PbMixin('TimestampMixin',
+      importFrom: 'package:protobuf/src/protobuf/mixins/well_known.dart',
+      injectedHelpers: [
+        '''
+/// Creates a new instance from [dateTime].
+///
+/// Time zone information will not be preserved.
+static Timestamp fromDateTime($_coreImportPrefix.DateTime dateTime) {
+  final result = create();
+  $_mixinImportPrefix.TimestampMixin.setFromDateTime(result, dateTime);
+  return result;
+}'''
+      ]),
 };
-
-WellKnownType wellKnownTypeForFullName(String fullName) =>
-    _wellKnownTypes[fullName];
diff --git a/protoc_plugin/test/goldens/grpc_service.pb b/protoc_plugin/test/goldens/grpc_service.pb
index 1976eb5..9954f5a 100644
--- a/protoc_plugin/test/goldens/grpc_service.pb
+++ b/protoc_plugin/test/goldens/grpc_service.pb
@@ -5,7 +5,7 @@
 // @dart = 2.3
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
diff --git a/protoc_plugin/test/goldens/grpc_service.pbgrpc b/protoc_plugin/test/goldens/grpc_service.pbgrpc
index c4bcc35..df64211 100644
--- a/protoc_plugin/test/goldens/grpc_service.pbgrpc
+++ b/protoc_plugin/test/goldens/grpc_service.pbgrpc
@@ -7,7 +7,7 @@
 
 import 'dart:async' as $async;
 
-import 'dart:core' as $core show int, String, List;
+import 'dart:core' as $core;
 
 import 'package:grpc/service_api.dart' as $grpc;
 import 'test.pb.dart' as $0;
diff --git a/protoc_plugin/test/goldens/header_in_package.pb b/protoc_plugin/test/goldens/header_in_package.pb
index 9360866..798978a 100644
--- a/protoc_plugin/test/goldens/header_in_package.pb
+++ b/protoc_plugin/test/goldens/header_in_package.pb
@@ -5,7 +5,7 @@
 // @dart = 2.3
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
diff --git a/protoc_plugin/test/goldens/header_with_fixnum.pb b/protoc_plugin/test/goldens/header_with_fixnum.pb
index b7aceb3..eb98d65 100644
--- a/protoc_plugin/test/goldens/header_with_fixnum.pb
+++ b/protoc_plugin/test/goldens/header_with_fixnum.pb
@@ -5,7 +5,7 @@
 // @dart = 2.3
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 import 'package:fixnum/fixnum.dart';
 import 'package:protobuf/protobuf.dart' as $pb;
diff --git a/protoc_plugin/test/goldens/imports.pb b/protoc_plugin/test/goldens/imports.pb
index 69888cf..27b8265 100644
--- a/protoc_plugin/test/goldens/imports.pb
+++ b/protoc_plugin/test/goldens/imports.pb
@@ -5,7 +5,7 @@
 // @dart = 2.3
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
diff --git a/protoc_plugin/test/goldens/oneMessage.pb b/protoc_plugin/test/goldens/oneMessage.pb
index e728680..fe417ad 100644
--- a/protoc_plugin/test/goldens/oneMessage.pb
+++ b/protoc_plugin/test/goldens/oneMessage.pb
@@ -5,7 +5,7 @@
 // @dart = 2.3
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
diff --git a/protoc_plugin/test/goldens/oneMessage.pb.meta b/protoc_plugin/test/goldens/oneMessage.pb.meta
index f9986a6..daba01c 100644
--- a/protoc_plugin/test/goldens/oneMessage.pb.meta
+++ b/protoc_plugin/test/goldens/oneMessage.pb.meta
@@ -2,15 +2,15 @@
   path: 4
   path: 0
   sourceFile: test
-  begin: 371
-  end: 382
+  begin: 299
+  end: 310
 }
 annotation: {
   path: 4
   path: 0
   sourceFile: test
-  begin: 636
-  end: 647
+  begin: 564
+  end: 575
 }
 annotation: {
   path: 4
@@ -18,8 +18,8 @@
   path: 2
   path: 0
   sourceFile: test
-  begin: 1564
-  end: 1570
+  begin: 1492
+  end: 1498
 }
 annotation: {
   path: 4
@@ -27,8 +27,8 @@
   path: 2
   path: 0
   sourceFile: test
-  begin: 1595
-  end: 1601
+  begin: 1523
+  end: 1529
 }
 annotation: {
   path: 4
@@ -36,8 +36,8 @@
   path: 2
   path: 0
   sourceFile: test
-  begin: 1654
-  end: 1663
+  begin: 1582
+  end: 1591
 }
 annotation: {
   path: 4
@@ -45,8 +45,8 @@
   path: 2
   path: 0
   sourceFile: test
-  begin: 1686
-  end: 1697
+  begin: 1614
+  end: 1625
 }
 annotation: {
   path: 4
@@ -54,8 +54,8 @@
   path: 2
   path: 1
   sourceFile: test
-  begin: 1735
-  end: 1739
+  begin: 1663
+  end: 1667
 }
 annotation: {
   path: 4
@@ -63,8 +63,8 @@
   path: 2
   path: 1
   sourceFile: test
-  begin: 1762
-  end: 1766
+  begin: 1690
+  end: 1694
 }
 annotation: {
   path: 4
@@ -72,8 +72,8 @@
   path: 2
   path: 1
   sourceFile: test
-  begin: 1821
-  end: 1828
+  begin: 1749
+  end: 1756
 }
 annotation: {
   path: 4
@@ -81,8 +81,8 @@
   path: 2
   path: 1
   sourceFile: test
-  begin: 1851
-  end: 1860
+  begin: 1779
+  end: 1788
 }
 annotation: {
   path: 4
@@ -90,8 +90,8 @@
   path: 2
   path: 2
   sourceFile: test
-  begin: 1901
-  end: 1905
+  begin: 1829
+  end: 1833
 }
 annotation: {
   path: 4
@@ -99,8 +99,8 @@
   path: 2
   path: 2
   sourceFile: test
-  begin: 1932
-  end: 1936
+  begin: 1860
+  end: 1864
 }
 annotation: {
   path: 4
@@ -108,8 +108,8 @@
   path: 2
   path: 2
   sourceFile: test
-  begin: 1989
-  end: 1996
+  begin: 1917
+  end: 1924
 }
 annotation: {
   path: 4
@@ -117,6 +117,6 @@
   path: 2
   path: 2
   sourceFile: test
-  begin: 2019
-  end: 2028
+  begin: 1947
+  end: 1956
 }
diff --git a/protoc_plugin/test/goldens/service.pb b/protoc_plugin/test/goldens/service.pb
index b56c969..e719f50 100644
--- a/protoc_plugin/test/goldens/service.pb
+++ b/protoc_plugin/test/goldens/service.pb
@@ -6,7 +6,7 @@
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
 import 'dart:async' as $async;
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
diff --git a/protoc_plugin/test/goldens/service.pbserver b/protoc_plugin/test/goldens/service.pbserver
index 6e44144..095c6d7 100644
--- a/protoc_plugin/test/goldens/service.pbserver
+++ b/protoc_plugin/test/goldens/service.pbserver
@@ -9,7 +9,7 @@
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
-import 'dart:core' as $core show String, Map, ArgumentError, dynamic;
+import 'dart:core' as $core;
 import 'test.pb.dart' as $0;
 import 'test.pbjson.dart';
 
diff --git a/protoc_plugin/test/goldens/topLevelEnum.pb b/protoc_plugin/test/goldens/topLevelEnum.pb
index 6c93b39..1c93619 100644
--- a/protoc_plugin/test/goldens/topLevelEnum.pb
+++ b/protoc_plugin/test/goldens/topLevelEnum.pb
@@ -5,7 +5,7 @@
 // @dart = 2.3
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
-import 'dart:core' as $core show bool, Deprecated, double, int, List, Map, override, pragma, String;
+import 'dart:core' as $core;
 
 export 'test.pbenum.dart';
 
diff --git a/protoc_plugin/test/goldens/topLevelEnum.pbenum b/protoc_plugin/test/goldens/topLevelEnum.pbenum
index 4b2b465..cee6e53 100644
--- a/protoc_plugin/test/goldens/topLevelEnum.pbenum
+++ b/protoc_plugin/test/goldens/topLevelEnum.pbenum
@@ -6,7 +6,7 @@
 // ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type
 
 // ignore_for_file: UNDEFINED_SHOWN_NAME,UNUSED_SHOWN_NAME
-import 'dart:core' as $core show int, dynamic, String, List, Map;
+import 'dart:core' as $core;
 import 'package:protobuf/protobuf.dart' as $pb;
 
 class PhoneType extends $pb.ProtobufEnum {
diff --git a/protoc_plugin/test/goldens/topLevelEnum.pbenum.meta b/protoc_plugin/test/goldens/topLevelEnum.pbenum.meta
index 603e31a..8a767c1 100644
--- a/protoc_plugin/test/goldens/topLevelEnum.pbenum.meta
+++ b/protoc_plugin/test/goldens/topLevelEnum.pbenum.meta
@@ -2,8 +2,8 @@
   path: 5
   path: 0
   sourceFile: test
-  begin: 394
-  end: 403
+  begin: 357
+  end: 366
 }
 annotation: {
   path: 5
@@ -11,8 +11,8 @@
   path: 2
   path: 0
   sourceFile: test
-  begin: 456
-  end: 462
+  begin: 419
+  end: 425
 }
 annotation: {
   path: 5
@@ -20,8 +20,8 @@
   path: 2
   path: 1
   sourceFile: test
-  begin: 516
-  end: 520
+  begin: 479
+  end: 483
 }
 annotation: {
   path: 5
@@ -29,8 +29,8 @@
   path: 2
   path: 2
   sourceFile: test
-  begin: 572
-  end: 576
+  begin: 535
+  end: 539
 }
 annotation: {
   path: 5
@@ -38,6 +38,6 @@
   path: 2
   path: 3
   sourceFile: test
-  begin: 629
-  end: 637
+  begin: 592
+  end: 600
 }
diff --git a/protobuf/test/mirror_util.dart b/protoc_plugin/test/mirror_util.dart
similarity index 100%
rename from protobuf/test/mirror_util.dart
rename to protoc_plugin/test/mirror_util.dart
diff --git a/protobuf/test/reserved_names_test.dart b/protoc_plugin/test/reserved_names_test.dart
similarity index 97%
rename from protobuf/test/reserved_names_test.dart
rename to protoc_plugin/test/reserved_names_test.dart
index 6c3dd6c..de682f6 100755
--- a/protobuf/test/reserved_names_test.dart
+++ b/protoc_plugin/test/reserved_names_test.dart
@@ -10,7 +10,7 @@
 
 import 'package:protobuf/meta.dart'
     show GeneratedMessage_reservedNames, ProtobufEnum_reservedNames;
-import 'package:protobuf/mixins_meta.dart' show findMixin;
+import 'package:protoc_plugin/mixins.dart' show findMixin;
 
 import 'mirror_util.dart' show findMemberNames;