diff --git a/Contrib/Makensisw/toolbar.cpp b/Contrib/Makensisw/toolbar.cpp
index c5c42042..13b1c36c 100644
--- a/Contrib/Makensisw/toolbar.cpp
+++ b/Contrib/Makensisw/toolbar.cpp
@@ -29,6 +29,12 @@
 #include "toolbar.h"
 #include "../ExDLL/nsis_tchar.h"
 
+#ifdef _countof
+#define COUNTOF _countof
+#else
+#define COUNTOF(a) (sizeof(a)/sizeof(a[0]))
+#endif
+
 NTOOLBAR g_toolbar;
 extern NSCRIPTDATA g_sdata;
 extern NTOOLTIP g_tip;