diff --git a/src/tint/utils/defer.h b/src/tint/utils/defer.h
index 4be704e961..ce586f94c7 100644
--- a/src/tint/utils/defer.h
+++ b/src/tint/utils/defer.h
@@ -19,8 +19,7 @@
 
 #include "src/tint/utils/concat.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// Defer executes a function or function like object when it is destructed.
 template <typename F>
@@ -51,8 +50,7 @@ inline Defer<F> MakeDefer(F&& f) {
   return Defer<F>(std::forward<F>(f));
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 /// TINT_DEFER(S) executes the statement(s) `S` when exiting the current lexical
 /// scope.
diff --git a/src/tint/utils/defer_test.cc b/src/tint/utils/defer_test.cc
index fe1034c4cf..27fd9b5ef3 100644
--- a/src/tint/utils/defer_test.cc
+++ b/src/tint/utils/defer_test.cc
@@ -16,8 +16,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(DeferTest, Basic) {
@@ -40,5 +39,4 @@ TEST(DeferTest, DeferOrder) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/enum_set.h b/src/tint/utils/enum_set.h
index a4fc621ae5..c5af0f9f07 100644
--- a/src/tint/utils/enum_set.h
+++ b/src/tint/utils/enum_set.h
@@ -21,8 +21,7 @@
 #include <type_traits>
 #include <utility>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// EnumSet is a set of enum values.
 /// @note As the EnumSet is backed by a single uint64_t value, it can only hold
@@ -237,8 +236,7 @@ inline std::ostream& operator<<(std::ostream& out, EnumSet<ENUM> set) {
   return out << "}";
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 namespace std {
 
diff --git a/src/tint/utils/enum_set_test.cc b/src/tint/utils/enum_set_test.cc
index 566701ca24..f0e4e67bea 100644
--- a/src/tint/utils/enum_set_test.cc
+++ b/src/tint/utils/enum_set_test.cc
@@ -19,8 +19,7 @@
 
 #include "gmock/gmock.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 using ::testing::ElementsAre;
@@ -240,5 +239,4 @@ TEST(EnumSetTest, Ostream) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/hash.h b/src/tint/utils/hash.h
index 1158021b10..e043e81fe8 100644
--- a/src/tint/utils/hash.h
+++ b/src/tint/utils/hash.h
@@ -20,8 +20,7 @@
 #include <functional>
 #include <vector>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace detail {
 
 /// Helper for obtaining a seed bias value for HashCombine with a bit-width
@@ -77,7 +76,6 @@ size_t Hash(const ARGS&... args) {
   return hash;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_HASH_H_
diff --git a/src/tint/utils/hash_test.cc b/src/tint/utils/hash_test.cc
index caeba57160..ec88a8ca23 100644
--- a/src/tint/utils/hash_test.cc
+++ b/src/tint/utils/hash_test.cc
@@ -18,8 +18,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(HashTests, Basic) {
@@ -45,5 +44,4 @@ TEST(HashTests, Vector) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/command.h b/src/tint/utils/io/command.h
index dbf587ef77..63ddab83a3 100644
--- a/src/tint/utils/io/command.h
+++ b/src/tint/utils/io/command.h
@@ -18,8 +18,7 @@
 #include <string>
 #include <utility>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// Command is a helper used by tests for executing a process with a number of
 /// arguments and an optional stdin string, and then collecting and returning
@@ -78,7 +77,6 @@ class Command {
   std::string input_;
 };
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_IO_COMMAND_H_
diff --git a/src/tint/utils/io/command_other.cc b/src/tint/utils/io/command_other.cc
index 5562e372a4..5ae73daaa9 100644
--- a/src/tint/utils/io/command_other.cc
+++ b/src/tint/utils/io/command_other.cc
@@ -14,8 +14,7 @@
 
 #include "src/tint/utils/io/command.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 Command::Command(const std::string&) {}
 
@@ -33,5 +32,4 @@ Command::Output Command::Exec(std::initializer_list<std::string>) const {
   return out;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/command_posix.cc b/src/tint/utils/io/command_posix.cc
index dc6068438c..3696921d2e 100644
--- a/src/tint/utils/io/command_posix.cc
+++ b/src/tint/utils/io/command_posix.cc
@@ -21,8 +21,7 @@
 #include <sstream>
 #include <vector>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 namespace {
 
@@ -261,5 +260,4 @@ Command::Output Command::Exec(
   }
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/command_test.cc b/src/tint/utils/io/command_test.cc
index f76dcaeee5..1b8bb83680 100644
--- a/src/tint/utils/io/command_test.cc
+++ b/src/tint/utils/io/command_test.cc
@@ -16,8 +16,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 #ifdef _WIN32
@@ -88,5 +87,4 @@ TEST(CommandTest, False) {
 #endif
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/command_windows.cc b/src/tint/utils/io/command_windows.cc
index 576fc4c3e1..d59f849c7c 100644
--- a/src/tint/utils/io/command_windows.cc
+++ b/src/tint/utils/io/command_windows.cc
@@ -19,8 +19,7 @@
 #include <sstream>
 #include <string>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 namespace {
 
@@ -245,5 +244,4 @@ Command::Output Command::Exec(
   return output;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/tmpfile.h b/src/tint/utils/io/tmpfile.h
index 07f48afd10..6f81a891e9 100644
--- a/src/tint/utils/io/tmpfile.h
+++ b/src/tint/utils/io/tmpfile.h
@@ -18,8 +18,7 @@
 #include <sstream>
 #include <string>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// TmpFile constructs a temporary file that can be written to, and is
 /// automatically deleted on destruction.
@@ -70,7 +69,6 @@ class TmpFile {
   std::string path_;
 };
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_IO_TMPFILE_H_
diff --git a/src/tint/utils/io/tmpfile_other.cc b/src/tint/utils/io/tmpfile_other.cc
index b4c1a18ee9..7ddbb58155 100644
--- a/src/tint/utils/io/tmpfile_other.cc
+++ b/src/tint/utils/io/tmpfile_other.cc
@@ -14,8 +14,7 @@
 
 #include "src/tint/utils/io/tmpfile.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 TmpFile::TmpFile(std::string) {}
 
@@ -25,5 +24,4 @@ bool TmpFile::Append(const void*, size_t) const {
   return false;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/tmpfile_posix.cc b/src/tint/utils/io/tmpfile_posix.cc
index db9ee47d83..00c20fe8da 100644
--- a/src/tint/utils/io/tmpfile_posix.cc
+++ b/src/tint/utils/io/tmpfile_posix.cc
@@ -19,8 +19,7 @@
 
 #include "src/tint/debug.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 namespace {
 
@@ -66,5 +65,4 @@ bool TmpFile::Append(const void* data, size_t size) const {
   return false;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/tmpfile_test.cc b/src/tint/utils/io/tmpfile_test.cc
index abd9511023..d312922f28 100644
--- a/src/tint/utils/io/tmpfile_test.cc
+++ b/src/tint/utils/io/tmpfile_test.cc
@@ -18,8 +18,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(TmpFileTest, WriteReadAppendDelete) {
@@ -86,5 +85,4 @@ TEST(TmpFileTest, FileExtension) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/io/tmpfile_windows.cc b/src/tint/utils/io/tmpfile_windows.cc
index 2b57b6878e..40dffc826d 100644
--- a/src/tint/utils/io/tmpfile_windows.cc
+++ b/src/tint/utils/io/tmpfile_windows.cc
@@ -17,8 +17,7 @@
 #include <stdio.h>
 #include <cstdio>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 namespace {
 
@@ -59,5 +58,4 @@ bool TmpFile::Append(const void* data, size_t size) const {
   return true;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/map.h b/src/tint/utils/map.h
index 0f60d13edc..12c93d4971 100644
--- a/src/tint/utils/map.h
+++ b/src/tint/utils/map.h
@@ -17,8 +17,7 @@
 
 #include <unordered_map>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// Lookup is a utility function for fetching a value from an unordered map if
 /// it exists, otherwise returning the `if_missing` argument.
@@ -56,7 +55,6 @@ V GetOrCreate(std::unordered_map<K, V, H, C>& map,
   return value;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_MAP_H_
diff --git a/src/tint/utils/map_test.cc b/src/tint/utils/map_test.cc
index a1e8decc83..ae35aeb36e 100644
--- a/src/tint/utils/map_test.cc
+++ b/src/tint/utils/map_test.cc
@@ -18,8 +18,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(Lookup, Test) {
@@ -54,5 +53,4 @@ TEST(GetOrCreateTest, ExistingKey) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/math.h b/src/tint/utils/math.h
index 155e39fb49..c6d7d461f0 100644
--- a/src/tint/utils/math.h
+++ b/src/tint/utils/math.h
@@ -19,8 +19,7 @@
 #include <string>
 #include <type_traits>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// @param alignment the next multiple to round `value` to
 /// @param value the value to round to the next multiple of `alignment`
@@ -51,7 +50,6 @@ inline std::enable_if_t<std::is_unsigned<T>::value, T> MaxAlignOf(T value) {
   return pot;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_MATH_H_
diff --git a/src/tint/utils/math_test.cc b/src/tint/utils/math_test.cc
index 057f142918..d6be3f6787 100644
--- a/src/tint/utils/math_test.cc
+++ b/src/tint/utils/math_test.cc
@@ -16,8 +16,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(MathTests, RoundUp) {
@@ -79,5 +78,4 @@ TEST(MathTests, MaxAlignOf) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/reverse.h b/src/tint/utils/reverse.h
index 17b1346a19..fb4f237cd0 100644
--- a/src/tint/utils/reverse.h
+++ b/src/tint/utils/reverse.h
@@ -17,8 +17,7 @@
 
 #include <iterator>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 namespace detail {
 /// Used by utils::Reverse to hold the underlying iterable.
@@ -58,7 +57,6 @@ detail::ReverseIterable<T> Reverse(T&& iterable) {
   return {iterable};
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_REVERSE_H_
diff --git a/src/tint/utils/reverse_test.cc b/src/tint/utils/reverse_test.cc
index 64734cdf4d..b23c799508 100644
--- a/src/tint/utils/reverse_test.cc
+++ b/src/tint/utils/reverse_test.cc
@@ -18,8 +18,7 @@
 
 #include "gmock/gmock.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(ReverseTest, Vector) {
@@ -32,5 +31,4 @@ TEST(ReverseTest, Vector) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/scoped_assignment.h b/src/tint/utils/scoped_assignment.h
index 0ff3421195..fdd787f1e5 100644
--- a/src/tint/utils/scoped_assignment.h
+++ b/src/tint/utils/scoped_assignment.h
@@ -20,8 +20,7 @@
 
 #include "src/tint/utils/concat.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// Helper class that temporarily assigns a value to a variable for the lifetime
 /// of the ScopedAssignment object. Once the ScopedAssignment is destructed, the
@@ -50,8 +49,7 @@ class ScopedAssignment {
   T old_value_;
 };
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 /// TINT_SCOPED_ASSIGNMENT(var, val) assigns `val` to `var`, and automatically
 /// restores the original value of `var` when exiting the current lexical scope.
diff --git a/src/tint/utils/scoped_assignment_test.cc b/src/tint/utils/scoped_assignment_test.cc
index 20cd8d003b..3055afe5d7 100644
--- a/src/tint/utils/scoped_assignment_test.cc
+++ b/src/tint/utils/scoped_assignment_test.cc
@@ -16,8 +16,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(ScopedAssignmentTest, Scopes) {
@@ -43,5 +42,4 @@ TEST(ScopedAssignmentTest, Scopes) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/string.h b/src/tint/utils/string.h
index 0355819c75..011e326c0c 100644
--- a/src/tint/utils/string.h
+++ b/src/tint/utils/string.h
@@ -17,8 +17,7 @@
 
 #include <string>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// @param str the string to apply replacements to
 /// @param substr the string to search for
@@ -35,7 +34,6 @@ inline std::string ReplaceAll(std::string str,
   return str;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_STRING_H_
diff --git a/src/tint/utils/string_test.cc b/src/tint/utils/string_test.cc
index 3dbb4861d5..f394ed73ee 100644
--- a/src/tint/utils/string_test.cc
+++ b/src/tint/utils/string_test.cc
@@ -16,8 +16,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(StringTest, ReplaceAll) {
@@ -34,5 +33,4 @@ TEST(StringTest, ReplaceAll) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/to_const_ptr_vec.h b/src/tint/utils/to_const_ptr_vec.h
index e36fe0c9ff..a46b3badef 100644
--- a/src/tint/utils/to_const_ptr_vec.h
+++ b/src/tint/utils/to_const_ptr_vec.h
@@ -18,8 +18,7 @@
 
 #include <vector>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// @param in a vector of `T*`
 /// @returns a vector of `const T*` with the content of `in`.
@@ -33,7 +32,6 @@ std::vector<const T*> ToConstPtrVec(const std::vector<T*>& in) {
   return out;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_TO_CONST_PTR_VEC_H_
diff --git a/src/tint/utils/transform.h b/src/tint/utils/transform.h
index 97711fddf0..29a9740893 100644
--- a/src/tint/utils/transform.h
+++ b/src/tint/utils/transform.h
@@ -22,8 +22,7 @@
 
 #include "src/tint/traits.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// Transform performs an element-wise transformation of a vector.
 /// @param in the input vector.
@@ -56,7 +55,6 @@ auto Transform(const std::vector<IN>& in, TRANSFORMER&& transform)
   return result;
 }
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_TRANSFORM_H_
diff --git a/src/tint/utils/transform_test.cc b/src/tint/utils/transform_test.cc
index 6686eeb200..e6688242b0 100644
--- a/src/tint/utils/transform_test.cc
+++ b/src/tint/utils/transform_test.cc
@@ -23,8 +23,7 @@
   static_assert(std::is_same<decltype(vector)::value_type, expected>::value, \
                 "unexpected result vector element type")
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(TransformTest, Empty) {
@@ -90,5 +89,4 @@ TEST(TransformTest, TransformDifferentType) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
diff --git a/src/tint/utils/unique_vector.h b/src/tint/utils/unique_vector.h
index 96d3ac3f7d..32d593ef0b 100644
--- a/src/tint/utils/unique_vector.h
+++ b/src/tint/utils/unique_vector.h
@@ -21,8 +21,7 @@
 #include <utility>
 #include <vector>
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 
 /// UniqueVector is an ordered container that only contains unique items.
 /// Attempting to add a duplicate is a no-op.
@@ -107,7 +106,6 @@ struct UniqueVector {
   std::unordered_set<T, HASH, EQUAL> set;
 };
 
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils
 
 #endif  // SRC_TINT_UTILS_UNIQUE_VECTOR_H_
diff --git a/src/tint/utils/unique_vector_test.cc b/src/tint/utils/unique_vector_test.cc
index 892282b240..c2c47a4067 100644
--- a/src/tint/utils/unique_vector_test.cc
+++ b/src/tint/utils/unique_vector_test.cc
@@ -17,8 +17,7 @@
 
 #include "gtest/gtest.h"
 
-namespace tint {
-namespace utils {
+namespace tint::utils {
 namespace {
 
 TEST(UniqueVectorTest, Empty) {
@@ -141,5 +140,4 @@ TEST(UniqueVectorTest, PopBack) {
 }
 
 }  // namespace
-}  // namespace utils
-}  // namespace tint
+}  // namespace tint::utils