diff --git a/src/system/boot/platform/atari_m68k/toscalls.h b/src/system/boot/platform/atari_m68k/toscalls.h
index d9e9ecd94f..f4a4df7e0c 100644
--- a/src/system/boot/platform/atari_m68k/toscalls.h
+++ b/src/system/boot/platform/atari_m68k/toscalls.h
@@ -9,6 +9,8 @@
 #ifndef _TOSCALLS_H
 #define _TOSCALLS_H
 
+#include <OS.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif