diff --git a/src/shims/time.h b/src/shims/time.h
index 063d52397..3d2d86e6f 100644
--- a/src/shims/time.h
+++ b/src/shims/time.h
@@ -148,7 +148,7 @@ _dispatch_uptime(void)
 	struct timespec ts;
 	dispatch_assume_zero(clock_gettime(CLOCK_UPTIME, &ts));
 	return _dispatch_timespec_to_nano(ts);
-#elif TARGET_OS_WIN32
+#elif defined(_WIN32)
 	LARGE_INTEGER now;
 	return QueryPerformanceCounter(&now) ? now.QuadPart : 0;
 #else