diff --git a/bench/BenchTimer.h b/bench/BenchTimer.h
index 7138bd91c..37b37e921 100644
--- a/bench/BenchTimer.h
+++ b/bench/BenchTimer.h
@@ -36,7 +36,7 @@
 #   define EIGEN_BT_UNDEF_WIN32_LEAN_AND_MEAN
 # endif
 # include <windows.h>
-#elif __APPLE__
+#elif defined(__APPLE__)
 #include <CoreServices/CoreServices.h>
 #include <mach/mach_time.h>
 #else