diff --git a/LEGO1/mxdirectx/mxstopwatch.h b/LEGO1/mxdirectx/mxstopwatch.h
index 0630d2f6..5a86b283 100644
--- a/LEGO1/mxdirectx/mxstopwatch.h
+++ b/LEGO1/mxdirectx/mxstopwatch.h
@@ -3,6 +3,7 @@
 
 #include "assert.h"
 
+#include <limits.h> // ULONG_MAX
 #include <math.h>
 #include <windows.h>