diff --git a/tools/replay/util.cc b/tools/replay/util.cc
index a08b3b3d5e..aaf73749d5 100644
--- a/tools/replay/util.cc
+++ b/tools/replay/util.cc
@@ -323,7 +323,7 @@ void precise_nano_sleep(int64_t nanoseconds, std::atomic<bool> &should_exit) {
   req.tv_sec = nanoseconds / 1000000000;
   req.tv_nsec = nanoseconds % 1000000000;
   while (!should_exit) {
-#ifdef __APPLE_
+#ifdef __APPLE__
     int ret = nanosleep(&req, &rem);
     if (ret == 0 || errno != EINTR)
       break;