diff --git a/msdos/int20.c b/msdos/int20.c
index f6be7ad..4743b74 100644
--- a/msdos/int20.c
+++ b/msdos/int20.c
@@ -3,6 +3,7 @@
  */
 
 #include <stdlib.h>
+#include "winbase.h"
 #include "miscemu.h"
 /* #define DEBUG_INT */
 #include "debug.h"