diff --git a/src/Makefile.inc b/src/Makefile.inc
index 935fc6c..c30c9f5 100644
--- a/src/Makefile.inc
+++ b/src/Makefile.inc
@@ -8,3 +8,4 @@
 AR = ar
 REMOVE = rm -rf
 
+FD_DEVICE = /dev/fd0
diff --git a/src/tools/Makefile b/src/tools/Makefile
index b77e430..574ae02 100644
--- a/src/tools/Makefile
+++ b/src/tools/Makefile
@@ -52,11 +52,11 @@
 	(cp ../bin/ld/ld.so ./)
 	#(cp /lib/libc.so.5 ./)
 	(cp ../bin/ttyd/ttyd ./)
-	(./format 50 2000 /dev/fd0 ubix.elf 0 login 3754 ROM8X14.DPF 3754 init 3754 ubistry 3754 shell 3754 userdb 3754 ls 3754 motd 3754 fdisk 3754 cp 3754 clock 3754 libc_old.so 3754 ld.so 3754 ttyd 3754 mbr 3754)
-#	(./format 50 2000 /dev/fd0 ubix.elf 0 login 3754 init 3754 ubistry 3754 shell 3754 userdb 3754 motd 3754 libc_old.so 3754 ld.so 3754 test 3754 libc.so.5 3754)
+	(./format 50 2000 ${FD_DEVICE} ubix.elf 0 login 3754 ROM8X14.DPF 3754 init 3754 ubistry 3754 shell 3754 userdb 3754 ls 3754 motd 3754 fdisk 3754 cp 3754 clock 3754 libc_old.so 3754 ld.so 3754 ttyd 3754 mbr 3754)
+#	(./format 50 2000 ${FD_DEVICE} ubix.elf 0 login 3754 init 3754 ubistry 3754 shell 3754 userdb 3754 motd 3754 libc_old.so 3754 ld.so 3754 test 3754 libc.so.5 3754)
 
 	#(./format 263 204361 /dev/md1 ubix.elf 0 format 3754 fdisk 3754 ROM8X14.DPF 3754 init 3754 login 3754 shell 3754 userdb 3754 ls 3754 motd 3754 cp 3754)
-	(./format 1064 2000 /dev/fd0 shell 3754 clock 3754)
+	(./format 1064 2000 ${FD_DEVICE} shell 3754 clock 3754)
 	#(./format 200 2000 /dev/md1 ubix.elf 0 shell 3754 motd 3754 libc_old.so 3754)
 	(rm -fr ubix.elf)
 	(rm -fr login)