Needs to include windef.h.

diff --git a/server/snapshot.c b/server/snapshot.c
index 3f806be..0a690eb 100644
--- a/server/snapshot.c
+++ b/server/snapshot.c
@@ -10,7 +10,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "winnt.h"
+#include "windef.h"
 #include "tlhelp32.h"
 
 #include "handle.h"