--- uae/src/serial.c	2018/04/24 16:39:50	1.1.1.3
+++ uae/src/serial.c	2018/04/24 16:56:24	1.1.1.5
@@ -16,7 +16,6 @@
 #include "uae.h"
 #include "memory.h"
 #include "custom.h"
-#include "readcpu.h"
 #include "newcpu.h"
 #include "cia.h"
 
@@ -389,8 +388,8 @@ void serial_open(void)
 
 void serial_close (void)
 {
-    if (sd != 0)
-	close(sd);
+    if (sd >= 0)
+	close (sd);
     serdev = 0;
 }