diff --git a/aos/testing/prevent_exit.h b/aos/testing/prevent_exit.h
index ee39fdb..75e8a1a 100644
--- a/aos/testing/prevent_exit.h
+++ b/aos/testing/prevent_exit.h
@@ -1,8 +1,7 @@
 #ifndef AOS_TESTING_PREVENT_EXIT_H_
 #define AOS_TESTING_PREVENT_EXIT_H_
 
-namespace aos {
-namespace testing {
+namespace aos::testing {
 
 // Registers an exit handler (using atexit(3)) which will call _exit(2).
 // Intended to be called in a freshly fork(2)ed process where it will run before
@@ -10,7 +9,6 @@
 // being run.
 void PreventExit();
 
-}  // namespace testing
-}  // namespace aos
+}  // namespace aos::testing
 
 #endif  // AOS_TESTING_PREVENT_EXIT_H_