diff --git a/mojo/edk/system/core_unittest.cc b/mojo/edk/system/core_unittest.cc
index b789301..c562097 100644
--- a/mojo/edk/system/core_unittest.cc
+++ b/mojo/edk/system/core_unittest.cc
@@ -24,7 +24,7 @@
                                       MOJO_HANDLE_SIGNAL_WRITABLE |
                                       MOJO_HANDLE_SIGNAL_PEER_CLOSED;
 
-typedef test::CoreTestBase CoreTest;
+using CoreTest = test::CoreTestBase;
 
 TEST_F(CoreTest, GetTimeTicksNow) {
   const MojoTimeTicks start = core()->GetTimeTicksNow();