diff --git a/aos/libc/aos_strerror_test.cc b/aos/libc/aos_strerror_test.cc
index abd867e..06a012a 100644
--- a/aos/libc/aos_strerror_test.cc
+++ b/aos/libc/aos_strerror_test.cc
@@ -4,9 +4,7 @@
 
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace libc {
-namespace testing {
+namespace aos::libc::testing {
 
 // Tries a couple of easy ones.
 TEST(StrerrorTest, Basic) {
@@ -24,6 +22,4 @@
   }
 }
 
-}  // namespace testing
-}  // namespace libc
-}  // namespace aos
+}  // namespace aos::libc::testing
diff --git a/aos/libc/aos_strsignal_test.cc b/aos/libc/aos_strsignal_test.cc
index d854aab..7e91d46 100644
--- a/aos/libc/aos_strsignal_test.cc
+++ b/aos/libc/aos_strsignal_test.cc
@@ -5,9 +5,7 @@
 
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace libc {
-namespace testing {
+namespace aos::libc::testing {
 
 // Tries a couple of easy ones.
 TEST(StrsignalTest, Basic) {
@@ -45,6 +43,4 @@
 }
 #endif
 
-}  // namespace testing
-}  // namespace libc
-}  // namespace aos
+}  // namespace aos::libc::testing
diff --git a/aos/libc/dirname.cc b/aos/libc/dirname.cc
index bc34496..e73030c 100644
--- a/aos/libc/dirname.cc
+++ b/aos/libc/dirname.cc
@@ -1,7 +1,6 @@
 #include "aos/libc/dirname.h"
 
-namespace aos {
-namespace libc {
+namespace aos::libc {
 namespace {
 
 ::std::string DoDirname(const ::std::string &path, size_t last_slash) {
@@ -35,5 +34,4 @@
   return DoDirname(path, last_slash);
 }
 
-}  // namespace libc
-}  // namespace aos
+}  // namespace aos::libc
diff --git a/aos/libc/dirname_test.cc b/aos/libc/dirname_test.cc
index d003936..501b752 100644
--- a/aos/libc/dirname_test.cc
+++ b/aos/libc/dirname_test.cc
@@ -4,9 +4,7 @@
 
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace libc {
-namespace testing {
+namespace aos::libc::testing {
 
 // Tests the examples from the Linux man-pages release 3.44 dirname(3).
 TEST(DirnameTest, ManPageExamples) {
@@ -74,6 +72,4 @@
   }
 }
 
-}  // namespace testing
-}  // namespace libc
-}  // namespace aos
+}  // namespace aos::libc::testing