diff --git a/pkgs/c_compiler/test/cbuilder/cbuilder_build_failure_test.dart b/pkgs/c_compiler/test/cbuilder/cbuilder_build_failure_test.dart
index 9891c4956f..9f16d38b92 100644
--- a/pkgs/c_compiler/test/cbuilder/cbuilder_build_failure_test.dart
+++ b/pkgs/c_compiler/test/cbuilder/cbuilder_build_failure_test.dart
@@ -2,7 +2,10 @@
 // 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.
 
-@OnPlatform({'windows': Timeout.factor(10)})
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+  'windows': Timeout.factor(10),
+})
 library;
 
 import 'dart:io';
diff --git a/pkgs/c_compiler/test/cbuilder/cbuilder_cross_ios_test.dart b/pkgs/c_compiler/test/cbuilder/cbuilder_cross_ios_test.dart
index 7fb1e6a39e..e4dcf00772 100644
--- a/pkgs/c_compiler/test/cbuilder/cbuilder_cross_ios_test.dart
+++ b/pkgs/c_compiler/test/cbuilder/cbuilder_cross_ios_test.dart
@@ -3,6 +3,9 @@
 // BSD-style license that can be found in the LICENSE file.
 
 @TestOn('mac-os')
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+})
 library;
 
 import 'dart:io';
diff --git a/pkgs/c_compiler/test/cbuilder/cbuilder_cross_macos_host_test.dart b/pkgs/c_compiler/test/cbuilder/cbuilder_cross_macos_host_test.dart
index b3d6ea8a57..06f4ff16f9 100644
--- a/pkgs/c_compiler/test/cbuilder/cbuilder_cross_macos_host_test.dart
+++ b/pkgs/c_compiler/test/cbuilder/cbuilder_cross_macos_host_test.dart
@@ -3,6 +3,9 @@
 // BSD-style license that can be found in the LICENSE file.
 
 @TestOn('mac-os')
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+})
 library;
 
 import 'dart:io';
diff --git a/pkgs/c_compiler/test/cbuilder/cbuilder_cross_windows_host_test.dart b/pkgs/c_compiler/test/cbuilder/cbuilder_cross_windows_host_test.dart
index fc77cf655e..230c9afbbf 100644
--- a/pkgs/c_compiler/test/cbuilder/cbuilder_cross_windows_host_test.dart
+++ b/pkgs/c_compiler/test/cbuilder/cbuilder_cross_windows_host_test.dart
@@ -3,7 +3,9 @@
 // BSD-style license that can be found in the LICENSE file.
 
 @TestOn('windows')
-@OnPlatform({'windows': Timeout.factor(10)})
+@OnPlatform({
+  'windows': Timeout.factor(10),
+})
 library;
 
 import 'dart:io';
diff --git a/pkgs/c_compiler/test/cbuilder/cbuilder_test.dart b/pkgs/c_compiler/test/cbuilder/cbuilder_test.dart
index 7379ec0e7d..42df4e8a42 100644
--- a/pkgs/c_compiler/test/cbuilder/cbuilder_test.dart
+++ b/pkgs/c_compiler/test/cbuilder/cbuilder_test.dart
@@ -2,7 +2,10 @@
 // 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.
 
-@OnPlatform({'windows': Timeout.factor(10)})
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+  'windows': Timeout.factor(10),
+})
 library;
 
 import 'dart:ffi';
diff --git a/pkgs/c_compiler/test/cbuilder/compiler_resolver_test.dart b/pkgs/c_compiler/test/cbuilder/compiler_resolver_test.dart
index 6a48785a53..ca66929ce9 100644
--- a/pkgs/c_compiler/test/cbuilder/compiler_resolver_test.dart
+++ b/pkgs/c_compiler/test/cbuilder/compiler_resolver_test.dart
@@ -2,7 +2,10 @@
 // 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.
 
-@OnPlatform({'windows': Timeout.factor(10)})
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+  'windows': Timeout.factor(10),
+})
 library;
 
 import 'package:c_compiler/src/cbuilder/compiler_resolver.dart';
diff --git a/pkgs/c_compiler/test/native_toolchain/apple_clang_test.dart b/pkgs/c_compiler/test/native_toolchain/apple_clang_test.dart
index 184e017fa3..998922c3b7 100644
--- a/pkgs/c_compiler/test/native_toolchain/apple_clang_test.dart
+++ b/pkgs/c_compiler/test/native_toolchain/apple_clang_test.dart
@@ -3,6 +3,9 @@
 // BSD-style license that can be found in the LICENSE file.
 
 @TestOn('mac-os')
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+})
 library;
 
 import 'dart:io';
diff --git a/pkgs/c_compiler/test/native_toolchain/xcode_test.dart b/pkgs/c_compiler/test/native_toolchain/xcode_test.dart
index 62cb1ad24c..3d75e38efe 100644
--- a/pkgs/c_compiler/test/native_toolchain/xcode_test.dart
+++ b/pkgs/c_compiler/test/native_toolchain/xcode_test.dart
@@ -3,6 +3,9 @@
 // BSD-style license that can be found in the LICENSE file.
 
 @TestOn('mac-os')
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+})
 library;
 
 import 'dart:io';
diff --git a/pkgs/native_assets_cli/test/example/native_add_test.dart b/pkgs/native_assets_cli/test/example/native_add_test.dart
index fda77c685b..2792f4516a 100644
--- a/pkgs/native_assets_cli/test/example/native_add_test.dart
+++ b/pkgs/native_assets_cli/test/example/native_add_test.dart
@@ -2,7 +2,10 @@
 // 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.
 
-@OnPlatform({'windows': Timeout.factor(10)})
+@OnPlatform({
+  'mac-os': Timeout.factor(2),
+  'windows': Timeout.factor(10),
+})
 library;
 
 import 'dart:io';