diff --git a/src/tint/writer/msl/generator.cc b/src/tint/writer/msl/generator.cc
index 715af8d392..ecb1b5719a 100644
--- a/src/tint/writer/msl/generator.cc
+++ b/src/tint/writer/msl/generator.cc
@@ -18,9 +18,7 @@
 
 #include "src/tint/writer/msl/generator_impl.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 
 Options::Options() = default;
 Options::~Options() = default;
@@ -61,6 +59,4 @@ Result Generate(const Program* program, const Options& options) {
   return result;
 }
 
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator.h b/src/tint/writer/msl/generator.h
index 27f99683d9..21f14e0c8c 100644
--- a/src/tint/writer/msl/generator.h
+++ b/src/tint/writer/msl/generator.h
@@ -24,15 +24,15 @@
 #include "src/tint/writer/array_length_from_uniform_options.h"
 #include "src/tint/writer/text.h"
 
-namespace tint {
-
 // Forward declarations
+namespace tint {
 class Program;
-
-namespace writer {
-namespace msl {
-
+namespace writer::msl {
 class GeneratorImpl;
+}  // namespace writer::msl
+}  // namespace tint
+
+namespace tint::writer::msl {
 
 /// Configuration options used for generating MSL.
 struct Options {
@@ -116,8 +116,6 @@ struct Result {
 /// @returns the resulting MSL and supplementary information
 Result Generate(const Program* program, const Options& options);
 
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
 
 #endif  // SRC_TINT_WRITER_MSL_GENERATOR_H_
diff --git a/src/tint/writer/msl/generator_impl.cc b/src/tint/writer/msl/generator_impl.cc
index 5807b70eb3..9aa48de823 100644
--- a/src/tint/writer/msl/generator_impl.cc
+++ b/src/tint/writer/msl/generator_impl.cc
@@ -79,9 +79,7 @@
 #include "src/tint/writer/float_to_string.h"
 #include "src/tint/writer/generate_external_texture_bindings.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 bool last_is_break_or_fallthrough(const ast::BlockStatement* stmts) {
@@ -3050,6 +3048,4 @@ bool GeneratorImpl::CallBuiltinHelper(std::ostream& out,
   return true;
 }
 
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl.h b/src/tint/writer/msl/generator_impl.h
index c973fe622f..f6e2c625a3 100644
--- a/src/tint/writer/msl/generator_impl.h
+++ b/src/tint/writer/msl/generator_impl.h
@@ -41,18 +41,15 @@
 #include "src/tint/writer/array_length_from_uniform_options.h"
 #include "src/tint/writer/text_generator.h"
 
-namespace tint {
-
 // Forward declarations
-namespace sem {
+namespace tint::sem {
 class Call;
 class Builtin;
 class TypeConstructor;
 class TypeConversion;
-}  // namespace sem
+}  // namespace tint::sem
 
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 
 /// The result of sanitizing a program for generation.
 struct SanitizedResult {
@@ -444,8 +441,6 @@ class GeneratorImpl : public TextGenerator {
   std::unordered_map<uint32_t, std::string> int_dot_funcs_;
 };
 
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
 
 #endif  // SRC_TINT_WRITER_MSL_GENERATOR_IMPL_H_
diff --git a/src/tint/writer/msl/generator_impl_array_accessor_test.cc b/src/tint/writer/msl/generator_impl_array_accessor_test.cc
index 3625c9382f..d87469ed67 100644
--- a/src/tint/writer/msl/generator_impl_array_accessor_test.cc
+++ b/src/tint/writer/msl/generator_impl_array_accessor_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -48,6 +46,4 @@ TEST_F(MslGeneratorImplTest, IndexAccessor_OfDref) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_assign_test.cc b/src/tint/writer/msl/generator_impl_assign_test.cc
index 655ca2e08c..d87a614088 100644
--- a/src/tint/writer/msl/generator_impl_assign_test.cc
+++ b/src/tint/writer/msl/generator_impl_assign_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -36,6 +34,4 @@ TEST_F(MslGeneratorImplTest, Emit_Assign) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_binary_test.cc b/src/tint/writer/msl/generator_impl_binary_test.cc
index f99aa3cc0f..796f1de65c 100644
--- a/src/tint/writer/msl/generator_impl_binary_test.cc
+++ b/src/tint/writer/msl/generator_impl_binary_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 struct BinaryData {
@@ -182,6 +180,4 @@ TEST_F(MslBinaryTest, ModVec3F32) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_bitcast_test.cc b/src/tint/writer/msl/generator_impl_bitcast_test.cc
index b5c9e72f14..fe51305e22 100644
--- a/src/tint/writer/msl/generator_impl_bitcast_test.cc
+++ b/src/tint/writer/msl/generator_impl_bitcast_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -33,6 +31,4 @@ TEST_F(MslGeneratorImplTest, EmitExpression_Bitcast) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_block_test.cc b/src/tint/writer/msl/generator_impl_block_test.cc
index 8e92726922..ac6aa5a57c 100644
--- a/src/tint/writer/msl/generator_impl_block_test.cc
+++ b/src/tint/writer/msl/generator_impl_block_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -52,6 +50,4 @@ TEST_F(MslGeneratorImplTest, Emit_Block_WithoutNewline) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_break_test.cc b/src/tint/writer/msl/generator_impl_break_test.cc
index 2a9d313ef6..806188b307 100644
--- a/src/tint/writer/msl/generator_impl_break_test.cc
+++ b/src/tint/writer/msl/generator_impl_break_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -34,6 +32,4 @@ TEST_F(MslGeneratorImplTest, Emit_Break) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_builtin_test.cc b/src/tint/writer/msl/generator_impl_builtin_test.cc
index 6e61597b16..09a98a722b 100644
--- a/src/tint/writer/msl/generator_impl_builtin_test.cc
+++ b/src/tint/writer/msl/generator_impl_builtin_test.cc
@@ -16,9 +16,7 @@
 #include "src/tint/sem/call.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using BuiltinType = sem::BuiltinType;
@@ -495,6 +493,4 @@ kernel void func() {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_builtin_texture_test.cc b/src/tint/writer/msl/generator_impl_builtin_texture_test.cc
index 61c0a22d46..4760526877 100644
--- a/src/tint/writer/msl/generator_impl_builtin_texture_test.cc
+++ b/src/tint/writer/msl/generator_impl_builtin_texture_test.cc
@@ -16,9 +16,7 @@
 #include "src/tint/ast/call_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 std::string expected_texture_overload(
@@ -300,6 +298,4 @@ INSTANTIATE_TEST_SUITE_P(
     testing::ValuesIn(ast::builtin::test::TextureOverloadCase::ValidCases()));
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_call_test.cc b/src/tint/writer/msl/generator_impl_call_test.cc
index 3460915fcd..1b6ce7a2af 100644
--- a/src/tint/writer/msl/generator_impl_call_test.cc
+++ b/src/tint/writer/msl/generator_impl_call_test.cc
@@ -15,9 +15,7 @@
 #include "src/tint/ast/call_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -77,6 +75,4 @@ TEST_F(MslGeneratorImplTest, EmitStatement_Call) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_case_test.cc b/src/tint/writer/msl/generator_impl_case_test.cc
index ca40a6430e..8822ea9c3c 100644
--- a/src/tint/writer/msl/generator_impl_case_test.cc
+++ b/src/tint/writer/msl/generator_impl_case_test.cc
@@ -15,9 +15,7 @@
 #include "src/tint/ast/fallthrough_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -103,6 +101,4 @@ TEST_F(MslGeneratorImplTest, Emit_Case_Default) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_cast_test.cc b/src/tint/writer/msl/generator_impl_cast_test.cc
index 0195d36117..80497c29d2 100644
--- a/src/tint/writer/msl/generator_impl_cast_test.cc
+++ b/src/tint/writer/msl/generator_impl_cast_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -55,6 +53,4 @@ TEST_F(MslGeneratorImplTest, EmitExpression_Cast_IntMin) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_constructor_test.cc b/src/tint/writer/msl/generator_impl_constructor_test.cc
index 2b507f2a60..cbe34e7699 100644
--- a/src/tint/writer/msl/generator_impl_constructor_test.cc
+++ b/src/tint/writer/msl/generator_impl_constructor_test.cc
@@ -15,9 +15,7 @@
 #include "gmock/gmock.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using ::testing::HasSubstr;
@@ -185,6 +183,4 @@ TEST_F(MslGeneratorImplTest, EmitConstructor_Type_Struct_Empty) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_continue_test.cc b/src/tint/writer/msl/generator_impl_continue_test.cc
index 895b3c10eb..b6618db5ad 100644
--- a/src/tint/writer/msl/generator_impl_continue_test.cc
+++ b/src/tint/writer/msl/generator_impl_continue_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -41,6 +39,4 @@ TEST_F(MslGeneratorImplTest, Emit_Continue) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_discard_test.cc b/src/tint/writer/msl/generator_impl_discard_test.cc
index 0468ed2442..aeea97d0be 100644
--- a/src/tint/writer/msl/generator_impl_discard_test.cc
+++ b/src/tint/writer/msl/generator_impl_discard_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -34,6 +32,4 @@ TEST_F(MslGeneratorImplTest, Emit_Discard) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_function_test.cc b/src/tint/writer/msl/generator_impl_function_test.cc
index 12c84218e3..41dcbf19df 100644
--- a/src/tint/writer/msl/generator_impl_function_test.cc
+++ b/src/tint/writer/msl/generator_impl_function_test.cc
@@ -16,9 +16,7 @@
 #include "src/tint/ast/variable_decl_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -708,6 +706,4 @@ kernel void b(device Data* tint_symbol_1 [[buffer(0)]]) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_identifier_test.cc b/src/tint/writer/msl/generator_impl_identifier_test.cc
index d5e7559a0e..ea7a61708d 100644
--- a/src/tint/writer/msl/generator_impl_identifier_test.cc
+++ b/src/tint/writer/msl/generator_impl_identifier_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -35,6 +33,4 @@ TEST_F(MslGeneratorImplTest, EmitIdentifierExpression) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_if_test.cc b/src/tint/writer/msl/generator_impl_if_test.cc
index 5ac9f8303a..ff0cabcb9b 100644
--- a/src/tint/writer/msl/generator_impl_if_test.cc
+++ b/src/tint/writer/msl/generator_impl_if_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -101,6 +99,4 @@ TEST_F(MslGeneratorImplTest, Emit_IfWithMultiple) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_import_test.cc b/src/tint/writer/msl/generator_impl_import_test.cc
index 0ed3fb8047..6cf2f76ac4 100644
--- a/src/tint/writer/msl/generator_impl_import_test.cc
+++ b/src/tint/writer/msl/generator_impl_import_test.cc
@@ -15,9 +15,7 @@
 #include "src/tint/sem/call.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -253,6 +251,4 @@ TEST_F(MslGeneratorImplTest, MslImportData_Determinant) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_loop_test.cc b/src/tint/writer/msl/generator_impl_loop_test.cc
index dc9b684953..e31b6402d2 100644
--- a/src/tint/writer/msl/generator_impl_loop_test.cc
+++ b/src/tint/writer/msl/generator_impl_loop_test.cc
@@ -15,9 +15,7 @@
 #include "src/tint/ast/variable_decl_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -347,6 +345,4 @@ TEST_F(MslGeneratorImplTest, Emit_ForLoopWithMultiStmtInitCondCont) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_member_accessor_test.cc b/src/tint/writer/msl/generator_impl_member_accessor_test.cc
index 3fa3b05fc0..21c637efaa 100644
--- a/src/tint/writer/msl/generator_impl_member_accessor_test.cc
+++ b/src/tint/writer/msl/generator_impl_member_accessor_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -59,6 +57,4 @@ TEST_F(MslGeneratorImplTest, EmitExpression_MemberAccessor_Swizzle_gbr) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_module_constant_test.cc b/src/tint/writer/msl/generator_impl_module_constant_test.cc
index e01b9894f8..8f419de401 100644
--- a/src/tint/writer/msl/generator_impl_module_constant_test.cc
+++ b/src/tint/writer/msl/generator_impl_module_constant_test.cc
@@ -15,9 +15,7 @@
 #include "src/tint/ast/id_attribute.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -61,6 +59,4 @@ constant float b [[function_constant(1)]];
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_return_test.cc b/src/tint/writer/msl/generator_impl_return_test.cc
index 13643061db..7b846af506 100644
--- a/src/tint/writer/msl/generator_impl_return_test.cc
+++ b/src/tint/writer/msl/generator_impl_return_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -46,6 +44,4 @@ TEST_F(MslGeneratorImplTest, Emit_ReturnWithValue) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_sanitizer_test.cc b/src/tint/writer/msl/generator_impl_sanitizer_test.cc
index fe39d96efd..abab3d2469 100644
--- a/src/tint/writer/msl/generator_impl_sanitizer_test.cc
+++ b/src/tint/writer/msl/generator_impl_sanitizer_test.cc
@@ -18,9 +18,7 @@
 #include "src/tint/ast/variable_decl_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using ::testing::HasSubstr;
@@ -256,6 +254,4 @@ TEST_F(MslSanitizerTest,
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_switch_test.cc b/src/tint/writer/msl/generator_impl_switch_test.cc
index dda99d08d5..eec4c24537 100644
--- a/src/tint/writer/msl/generator_impl_switch_test.cc
+++ b/src/tint/writer/msl/generator_impl_switch_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -57,6 +55,4 @@ TEST_F(MslGeneratorImplTest, Emit_Switch) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_test.cc b/src/tint/writer/msl/generator_impl_test.cc
index 26085e37aa..cad1eb17b2 100644
--- a/src/tint/writer/msl/generator_impl_test.cc
+++ b/src/tint/writer/msl/generator_impl_test.cc
@@ -15,9 +15,7 @@
 #include "src/tint/ast/stage_attribute.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslGeneratorImplTest = TestHelper;
@@ -412,6 +410,4 @@ kernel void main4_no_usages() {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_type_test.cc b/src/tint/writer/msl/generator_impl_type_test.cc
index b59ca32d74..1efffbb1bd 100644
--- a/src/tint/writer/msl/generator_impl_type_test.cc
+++ b/src/tint/writer/msl/generator_impl_type_test.cc
@@ -24,9 +24,7 @@
 #include "src/tint/sem/storage_texture_type.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using ::testing::HasSubstr;
@@ -842,6 +840,4 @@ INSTANTIATE_TEST_SUITE_P(
                                           "texture3d<float, access::write>"}));
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_unary_op_test.cc b/src/tint/writer/msl/generator_impl_unary_op_test.cc
index 1d294e7d2c..c40183d9b2 100644
--- a/src/tint/writer/msl/generator_impl_unary_op_test.cc
+++ b/src/tint/writer/msl/generator_impl_unary_op_test.cc
@@ -14,9 +14,7 @@
 
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using MslUnaryOpTest = TestHelper;
@@ -101,6 +99,4 @@ TEST_F(MslUnaryOpTest, NegationOfIntMin) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/generator_impl_variable_decl_statement_test.cc b/src/tint/writer/msl/generator_impl_variable_decl_statement_test.cc
index 2e6f360dc6..ce26ab91d6 100644
--- a/src/tint/writer/msl/generator_impl_variable_decl_statement_test.cc
+++ b/src/tint/writer/msl/generator_impl_variable_decl_statement_test.cc
@@ -16,9 +16,7 @@
 #include "src/tint/ast/variable_decl_statement.h"
 #include "src/tint/writer/msl/test_helper.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 namespace {
 
 using ::testing::HasSubstr;
@@ -164,6 +162,4 @@ TEST_F(MslGeneratorImplTest, Emit_VariableDeclStatement_Initializer_ZeroVec) {
 }
 
 }  // namespace
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
diff --git a/src/tint/writer/msl/test_helper.h b/src/tint/writer/msl/test_helper.h
index 2e0f3f1eb2..88f1ff5cf5 100644
--- a/src/tint/writer/msl/test_helper.h
+++ b/src/tint/writer/msl/test_helper.h
@@ -24,9 +24,7 @@
 #include "src/tint/writer/msl/generator.h"
 #include "src/tint/writer/msl/generator_impl.h"
 
-namespace tint {
-namespace writer {
-namespace msl {
+namespace tint::writer::msl {
 
 /// Helper class for testing
 template <typename BASE>
@@ -101,8 +99,6 @@ using TestHelper = TestHelperBase<testing::Test>;
 template <typename T>
 using TestParamHelper = TestHelperBase<testing::TestWithParam<T>>;
 
-}  // namespace msl
-}  // namespace writer
-}  // namespace tint
+}  // namespace tint::writer::msl
 
 #endif  // SRC_TINT_WRITER_MSL_TEST_HELPER_H_