diff --git a/sys/amd64/include/iodev.h b/sys/amd64/include/iodev.h
index 2273620ccba4..4b35d8b03fa2 100644
--- a/sys/amd64/include/iodev.h
+++ b/sys/amd64/include/iodev.h
@@ -26,8 +26,5 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
-#define CDEV_MINOR_IO	14
-
 d_open_t	ioopen;
 d_close_t	ioclose;
diff --git a/sys/amd64/include/memdev.h b/sys/amd64/include/memdev.h
index b6d31220cb93..97000c951b29 100644
--- a/sys/amd64/include/memdev.h
+++ b/sys/amd64/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1
 
diff --git a/sys/arm/include/memdev.h b/sys/arm/include/memdev.h
index 9cf0b4ae7e26..d32432e01cf6 100644
--- a/sys/arm/include/memdev.h
+++ b/sys/arm/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1
 
diff --git a/sys/dev/io/iodev.c b/sys/dev/io/iodev.c
index 33f6c1d099b9..7c7ee9cae456 100644
--- a/sys/dev/io/iodev.c
+++ b/sys/dev/io/iodev.c
@@ -66,7 +66,7 @@ io_modevent(module_t mod __unused, int type, void *data __unused)
 	case MOD_LOAD:
 		if (bootverbose)
 			printf("io: <I/O>\n");
-		iodev = make_dev(&io_cdevsw, CDEV_MINOR_IO,
+		iodev = make_dev(&io_cdevsw, 0,
 			UID_ROOT, GID_WHEEL, 0600, "io");
 		break;
 
diff --git a/sys/i386/include/iodev.h b/sys/i386/include/iodev.h
index 2273620ccba4..4b35d8b03fa2 100644
--- a/sys/i386/include/iodev.h
+++ b/sys/i386/include/iodev.h
@@ -26,8 +26,5 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
-#define CDEV_MINOR_IO	14
-
 d_open_t	ioopen;
 d_close_t	ioclose;
diff --git a/sys/i386/include/memdev.h b/sys/i386/include/memdev.h
index 4443e3605cbe..eafa9cc26c94 100644
--- a/sys/i386/include/memdev.h
+++ b/sys/i386/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1
 
diff --git a/sys/ia64/include/memdev.h b/sys/ia64/include/memdev.h
index 32cc1fc1f422..d4f0eb3d0cb0 100644
--- a/sys/ia64/include/memdev.h
+++ b/sys/ia64/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1
 
diff --git a/sys/mips/include/iodev.h b/sys/mips/include/iodev.h
index 2273620ccba4..4b35d8b03fa2 100644
--- a/sys/mips/include/iodev.h
+++ b/sys/mips/include/iodev.h
@@ -26,8 +26,5 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
-#define CDEV_MINOR_IO	14
-
 d_open_t	ioopen;
 d_close_t	ioclose;
diff --git a/sys/mips/include/memdev.h b/sys/mips/include/memdev.h
index 6a7e9edfcc7a..2872fb07298b 100644
--- a/sys/mips/include/memdev.h
+++ b/sys/mips/include/memdev.h
@@ -27,7 +27,6 @@
  * $FreeBSD$
  */
 
-#define	CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM 1
 
diff --git a/sys/powerpc/include/memdev.h b/sys/powerpc/include/memdev.h
index 69072d9889ca..26dcaa87514e 100644
--- a/sys/powerpc/include/memdev.h
+++ b/sys/powerpc/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1
 
diff --git a/sys/sparc64/include/memdev.h b/sys/sparc64/include/memdev.h
index 671a6b467d7e..2186c5dbe8f3 100644
--- a/sys/sparc64/include/memdev.h
+++ b/sys/sparc64/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1
 
diff --git a/sys/sun4v/include/memdev.h b/sys/sun4v/include/memdev.h
index 671a6b467d7e..2186c5dbe8f3 100644
--- a/sys/sun4v/include/memdev.h
+++ b/sys/sun4v/include/memdev.h
@@ -26,7 +26,6 @@
  * $FreeBSD$
  */
 
-#define CDEV_MAJOR	2
 #define	CDEV_MINOR_MEM	0
 #define	CDEV_MINOR_KMEM	1