diff --git a/src/devices/system.h b/src/devices/system.h
index 36c2cb3..48fc5d4 100644
--- a/src/devices/system.h
+++ b/src/devices/system.h
@@ -11,7 +11,7 @@ WITH REGARD TO THIS SOFTWARE.
 
 #define SYSTEM_VERSION 1
 #define SYSTEM_DEIMASK 0x0000
-#define SYSTEM_DEOMASK 0xff28
+#define SYSTEM_DEOMASK 0xff08
 
 #define RAM_PAGES 0x10