diff --git a/include/dos_inc.h b/include/dos_inc.h
index 48bc6aba..fbc98df4 100644
--- a/include/dos_inc.h
+++ b/include/dos_inc.h
@@ -418,6 +418,9 @@ private:
 extern DOS_InfoBlock dos_infoblock;;
 
 INLINE Bit8u RealHandle(Bit16u handle) {
+	
+	// test out of range
+	if (handle>0xFF) return 0xff;
 	DOS_PSP psp(dos.psp);	
 	return psp.GetFileHandle((Bit8u)handle);
 }