diff --git a/include/minix/callnr.h b/include/minix/callnr.h
index a2243d3b3..40459736d 100644
--- a/include/minix/callnr.h
+++ b/include/minix/callnr.h
@@ -353,7 +353,7 @@
 #define VFS_MKNOD_NAME		m1_p1	/* const char * */
 #define VFS_MKNOD_LEN		m1_i1	/* size_t */
 #define VFS_MKNOD_MODE		m1_i2	/* mode_t */
-#define VFS_MKNOD_DEV		m1_i3	/* dev_t */
+#define VFS_MKNOD_DEV		m1_ull1	/* dev_t */
 
 /* Field names for the open(2), chdir(2), chmod(2), chroot(2), rmdir(2), and
  * unlink(2) calls.
diff --git a/include/minix/ipc.h b/include/minix/ipc.h
index 41076375e..4fa5bbf21 100644
--- a/include/minix/ipc.h
+++ b/include/minix/ipc.h
@@ -17,9 +17,10 @@
 #define M3_LONG_STRING    44	/* current m3_ca1 size (may be increased) */
 
 typedef struct {
+	uint64_t m1ull1;
 	int m1i1, m1i2, m1i3;
 	char *m1p1, *m1p2, *m1p3, *m1p4;
-	uint8_t padding[28];
+	uint8_t padding[20];
 } mess_1;
 _ASSERT_MSG_SIZE(mess_1);
 
@@ -28,7 +29,7 @@ typedef struct {
 	long m2l1, m2l2;
 	char *m2p1;
 	sigset_t sigset;
-        short m2s1;
+	short m2s1;
 	uint8_t padding[14];
 } mess_2;
 _ASSERT_MSG_SIZE(mess_2);
@@ -89,9 +90,10 @@ typedef struct {
 _ASSERT_MSG_SIZE(mess_8);
 
 typedef struct {
+	uint64_t m9ull1;
 	long m9l1, m9l2, m9l3, m9l4, m9l5;
 	short m9s1, m9s2, m9s3, m9s4;
-	uint8_t padding[28];
+	uint8_t padding[20];
 } mess_9;
 _ASSERT_MSG_SIZE(mess_9);
 
@@ -111,15 +113,15 @@ typedef struct {
 _ASSERT_MSG_SIZE(mess_11);
 
 typedef struct {
+	dev_t dev;	/* 64bits long. */
 	void *block;
 	u32_t dev_offset_pages;
 	u32_t ino_offset_pages;
 	u32_t ino;
 	u32_t *flags_ptr;
-	u32_t dev;
 	u8_t pages;
 	u8_t flags;
-	uint8_t padding[30];
+	uint8_t padding[26];
 } mess_vmmcp;
 _ASSERT_MSG_SIZE(mess_vmmcp);
 
@@ -134,13 +136,13 @@ _ASSERT_MSG_SIZE(mess_notify);
 typedef struct {
 	endpoint_t who;
 	u32_t offset;
-	u32_t dev;
+	dev_t dev;
 	u32_t ino;
 	u32_t vaddr;
 	u32_t len;
 	u16_t fd;
 	u16_t clearend_and_flags; /* low 12 bits are clearend, rest flags */
-	uint8_t padding[28];
+	uint8_t padding[24];
 } mess_vm_vfs_mmap;
 _ASSERT_MSG_SIZE(mess_vm_vfs_mmap);
 
@@ -186,6 +188,7 @@ typedef int _ASSERT_message[/* CONSTCOND */sizeof(message) == 64 ?1 : -1];
 #define m1_p2  m_u.m_m1.m1p2
 #define m1_p3  m_u.m_m1.m1p3
 #define m1_p4  m_u.m_m1.m1p4
+#define m1_ull1  m_u.m_m1.m1ull1
 
 #define m2_i1  m_u.m_m2.m2i1
 #define m2_i2  m_u.m_m2.m2i2
@@ -251,6 +254,7 @@ typedef int _ASSERT_message[/* CONSTCOND */sizeof(message) == 64 ?1 : -1];
 #define m9_s2  m_u.m_m9.m9s2
 #define m9_s3  m_u.m_m9.m9s3
 #define m9_s4  m_u.m_m9.m9s4
+#define m9_ull1  m_u.m_m9.m9ull1
 
 #define m10_i1 m_u.m_m10.m10i1
 #define m10_i2 m_u.m_m10.m10i2
diff --git a/include/minix/rs.h b/include/minix/rs.h
index 6a499f55c..f5f8621d6 100644
--- a/include/minix/rs.h
+++ b/include/minix/rs.h
@@ -118,7 +118,7 @@ struct rprocpub {
   unsigned sys_flags; 		  /* sys flags */
   endpoint_t endpoint;		  /* process endpoint number */
 
-  dev_t dev_nr;			  /* major device number or NO_DEV */
+  devmajor_t dev_nr;		  /* major device number or NO_DEV */
 
   char label[RS_MAX_LABEL_LEN];	  /* label of this service */
   char proc_name[RS_MAX_LABEL_LEN]; /* process name of this service */
diff --git a/include/minix/vfsif.h b/include/minix/vfsif.h
index 7e2f0aead..e12837676 100644
--- a/include/minix/vfsif.h
+++ b/include/minix/vfsif.h
@@ -8,8 +8,7 @@
 #define REQ_ACTIME		m9_l2
 #define REQ_ACNSEC		m9_l4
 #define REQ_COUNT		m9_l2
-#define REQ_DEV			m9_l5
-#define REQ_DEV2		m9_l1
+#define REQ_DEV			m9_ull1
 #define REQ_DIR_INO   		m9_l3
 #define REQ_FLAGS		m9_s3
 #define REQ_GID			m9_s1
@@ -41,7 +40,7 @@
 #define REQ_UID			m9_s4
 
 /* VFS/FS reply fields */
-#define RES_DEV			m9_l4
+#define RES_DEV			m9_ull1
 #define RES_GID			m9_s1
 #define RES_INODE_NR		m9_l1
 #define RES_FILE_SIZE_HI	m9_l2
diff --git a/include/minix/vm.h b/include/minix/vm.h
index 63bca2b81..b86b365b9 100644
--- a/include/minix/vm.h
+++ b/include/minix/vm.h
@@ -24,7 +24,7 @@ int vm_watch_exit(endpoint_t ep);
 int vm_forgetblock(u64_t id);
 void vm_forgetblocks(void);
 int minix_vfs_mmap(endpoint_t who, u32_t offset, u32_t len,
-        u32_t dev, u32_t ino, u16_t fd, u32_t vaddr, u16_t clearend, u16_t
+        dev_t dev, u32_t ino, u16_t fd, u32_t vaddr, u16_t clearend, u16_t
 	flags);
 
 /* minix vfs mmap flags */
@@ -65,13 +65,13 @@ int vm_info_region(endpoint_t who, struct vm_region_info *vri, int
 	count, vir_bytes *next);
 int vm_procctl(endpoint_t ep, int param);
 
-int vm_set_cacheblock(void *block, u32_t dev, u64_t dev_offset,
+int vm_set_cacheblock(void *block, dev_t dev, u64_t dev_offset,
         u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize);
 
-void *vm_map_cacheblock(u32_t dev, u64_t dev_offset,
+void *vm_map_cacheblock(dev_t dev, u64_t dev_offset,
         u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize);
 
-int vm_clear_cache(u32_t dev);
+int vm_clear_cache(dev_t dev);
 
 /* flags for vm cache functions */
 #define VMMC_FLAGS_LOCKED	0x01	/* someone is updating the flags; don't read/write */
diff --git a/lib/libc/sys-minix/mmap.c b/lib/libc/sys-minix/mmap.c
index bdf97ff84..e694f67ff 100644
--- a/lib/libc/sys-minix/mmap.c
+++ b/lib/libc/sys-minix/mmap.c
@@ -53,7 +53,7 @@ void *minix_mmap_for(endpoint_t forwhom,
 }
 
 int minix_vfs_mmap(endpoint_t who, u32_t offset, u32_t len,
-	u32_t dev, u32_t ino, u16_t fd, u32_t vaddr, u16_t clearend,
+	dev_t dev, u32_t ino, u16_t fd, u32_t vaddr, u16_t clearend,
 	u16_t flags)
 {
 	message m;
diff --git a/lib/libminixfs/cache.c b/lib/libminixfs/cache.c
index 1968918ed..6e16ce19e 100644
--- a/lib/libminixfs/cache.c
+++ b/lib/libminixfs/cache.c
@@ -479,7 +479,7 @@ int block_type;			/* INODE_BLOCK, DIRECTORY_BLOCK, or whatever */
 			printf("libminixfs: ENOSYS, disabling VM calls\n");
 			vmcache = 0;
 		} else {
-			panic("libminixfs: setblock of %p dev 0x%x off "
+			panic("libminixfs: setblock of %p dev 0x%llx off "
 				"0x%llx failed\n", bp->data, dev, dev_off);
 		}
 	}
@@ -940,7 +940,7 @@ int lmfs_rdwt_err(void)
 int lmfs_do_bpeek(message *m)
 {
 	block_t startblock, b, limitblock;
-	dev_t dev = m->REQ_DEV2;
+	dev_t dev = m->REQ_DEV;
 	u64_t extra, pos = make64(m->REQ_SEEK_POS_LO, m->REQ_SEEK_POS_HI);
 	size_t len = m->REQ_NBYTES;
 	struct buf *bp;
diff --git a/lib/libpuffs/misc.c b/lib/libpuffs/misc.c
index 4de047ee7..e5886ebcb 100644
--- a/lib/libpuffs/misc.c
+++ b/lib/libpuffs/misc.c
@@ -41,7 +41,7 @@ int fs_flush()
  * to disk.
  */
 #if 0
-  dev_t dev = (dev_t) fs_m_in.REQ_DEV;
+  dev_t dev = fs_m_in.REQ_DEV;
 
   if(dev == fs_dev) return(EBUSY);
 
diff --git a/lib/libpuffs/open.c b/lib/libpuffs/open.c
index f1f7c2508..8888259f4 100644
--- a/lib/libpuffs/open.c
+++ b/lib/libpuffs/open.c
@@ -161,7 +161,7 @@ int fs_mknod()
   va.va_mode = (mode_t) fs_m_in.REQ_MODE;
   va.va_uid = caller_uid;
   va.va_gid = caller_gid;
-  va.va_rdev = (dev_t) fs_m_in.REQ_DEV;
+  va.va_rdev = fs_m_in.REQ_DEV;
   va.va_atime = va.va_mtime = va.va_ctime = cur_time;
 
   if (buildpath) {
diff --git a/lib/libsffs/mount.c b/lib/libsffs/mount.c
index a2212d0ba..2ed02d191 100644
--- a/lib/libsffs/mount.c
+++ b/lib/libsffs/mount.c
@@ -23,7 +23,7 @@ int do_readsuper()
   int r;
 
   dprintf(("%s: readsuper (dev %x, flags %x)\n",
-	sffs_name, (dev_t) m_in.REQ_DEV, m_in.REQ_FLAGS));
+	sffs_name, m_in.REQ_DEV, m_in.REQ_FLAGS));
 
   if (m_in.REQ_FLAGS & REQ_ISROOT) {
 	printf("%s: attempt to mount as root device\n", sffs_name);
diff --git a/lib/libsys/vm_cache.c b/lib/libsys/vm_cache.c
index 171ba39c8..f4ee89829 100644
--- a/lib/libsys/vm_cache.c
+++ b/lib/libsys/vm_cache.c
@@ -9,7 +9,7 @@
 #include <minix/sysutil.h>
 #include <machine/vmparam.h>
 
-int vm_cachecall(message *m, int call, void *addr, u32_t dev, u64_t dev_offset,
+int vm_cachecall(message *m, int call, void *addr, dev_t dev, u64_t dev_offset,
 	u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize)
 {
     if(blocksize % PAGE_SIZE)
@@ -40,7 +40,7 @@ int vm_cachecall(message *m, int call, void *addr, u32_t dev, u64_t dev_offset,
     return _taskcall(VM_PROC_NR, call, m);
 }
 
-void *vm_map_cacheblock(u32_t dev, u64_t dev_offset,
+void *vm_map_cacheblock(dev_t dev, u64_t dev_offset,
 	u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize)
 {
 	message m;
@@ -52,7 +52,7 @@ void *vm_map_cacheblock(u32_t dev, u64_t dev_offset,
 	return m.m_u.m_vmmcp_reply.addr;
 }
 
-int vm_set_cacheblock(void *block, u32_t dev, u64_t dev_offset,
+int vm_set_cacheblock(void *block, dev_t dev, u64_t dev_offset,
 	u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize)
 {
 	message m;
@@ -62,7 +62,7 @@ int vm_set_cacheblock(void *block, u32_t dev, u64_t dev_offset,
 }
 
 int
-vm_clear_cache(u32_t dev)
+vm_clear_cache(dev_t dev)
 {
 	message m;
 
diff --git a/servers/ext2/inode.c b/servers/ext2/inode.c
index 9f97359eb..0fdc3f38e 100644
--- a/servers/ext2/inode.c
+++ b/servers/ext2/inode.c
@@ -41,7 +41,7 @@ int fs_putnode(void)
   rip = find_inode(fs_dev, (pino_t) fs_m_in.REQ_INODE_NR);
 
   if (!rip) {
-	printf("%s:%d put_inode: inode #%u dev: %d not found\n", __FILE__,
+	printf("%s:%d put_inode: inode #%u dev: %llx not found\n", __FILE__,
 		__LINE__, (pino_t) fs_m_in.REQ_INODE_NR, fs_dev);
 	panic("fs_putnode failed");
   }
diff --git a/servers/ext2/misc.c b/servers/ext2/misc.c
index f0127889d..6902df25a 100644
--- a/servers/ext2/misc.c
+++ b/servers/ext2/misc.c
@@ -49,7 +49,7 @@ int fs_flush()
 /* Flush the blocks of a device from the cache after writing any dirty blocks
  * to disk.
  */
-  dev_t dev = (dev_t) fs_m_in.REQ_DEV;
+  dev_t dev = fs_m_in.REQ_DEV;
 
   if(dev == fs_dev) return(EBUSY);
 
@@ -71,7 +71,7 @@ int fs_new_driver(void)
   char label[sizeof(fs_dev_label)];
   int r;
 
-  dev = (dev_t) fs_m_in.REQ_DEV;
+  dev = fs_m_in.REQ_DEV;
   label_gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
   label_len = (size_t) fs_m_in.REQ_PATH_LEN;
 
diff --git a/servers/ext2/read.c b/servers/ext2/read.c
index b8c9a424f..b4c505d38 100644
--- a/servers/ext2/read.c
+++ b/servers/ext2/read.c
@@ -164,9 +164,9 @@ int fs_breadwrite(void)
                     (unsigned long) fs_m_in.REQ_SEEK_POS_HI);
   nrbytes = (size_t) fs_m_in.REQ_NBYTES;
 
-  block_size = get_block_size( (dev_t) fs_m_in.REQ_DEV2);
+  block_size = get_block_size(fs_m_in.REQ_DEV);
 
-  rip.i_block[0] = (block_t) fs_m_in.REQ_DEV2;
+  rip.i_block[0] = (block_t) fs_m_in.REQ_DEV;
   rip.i_mode = I_BLOCK_SPECIAL;
   rip.i_size = 0;
 
diff --git a/servers/ext2/stadir.c b/servers/ext2/stadir.c
index cc08c872f..f99d54efb 100644
--- a/servers/ext2/stadir.c
+++ b/servers/ext2/stadir.c
@@ -43,7 +43,7 @@ static int stat_inode(
   statbuf.st_nlink = rip->i_links_count;
   statbuf.st_uid = rip->i_uid;
   statbuf.st_gid = rip->i_gid;
-  statbuf.st_rdev = (s ? rip->i_block[0] : NO_DEV);
+  statbuf.st_rdev = (s ? (dev_t)rip->i_block[0] : NO_DEV);
   statbuf.st_size = rip->i_size;
   statbuf.st_atime = rip->i_atime;
   statbuf.st_mtime = rip->i_mtime;
diff --git a/servers/iso9660fs/misc.c b/servers/iso9660fs/misc.c
index 7c7c9eb91..456f20157 100644
--- a/servers/iso9660fs/misc.c
+++ b/servers/iso9660fs/misc.c
@@ -26,7 +26,7 @@ int fs_new_driver(void)
   char label[sizeof(fs_dev_label)];
   int r;
 
-  dev = (dev_t) fs_m_in.REQ_DEV;
+  dev = fs_m_in.REQ_DEV;
   label_gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
   label_len = (size_t) fs_m_in.REQ_PATH_LEN;
 
diff --git a/servers/lwip/inet_config.c b/servers/lwip/inet_config.c
index d4ec68f10..1f7009f45 100644
--- a/servers/lwip/inet_config.c
+++ b/servers/lwip/inet_config.c
@@ -56,11 +56,11 @@ static void check_mknod(const char *device, mode_t mode, int minor)
 {
 	dev_t dev;
 
-	dev= (ip_dev & 0xFF00) | minor;
+	dev= makedev(major(ip_dev), minor);
 
 	unlink(device);
 	if (mknod(device, S_IFCHR | mode, dev) < 0) fatal(device);
-	printf("mknod %s c %d %d\n", device, (ip_dev >> 8), minor);
+	printf("mknod %s c %d %d\n", device, major(ip_dev), minor);
 }
 
 static int cfg_fd;
diff --git a/servers/mfs/inode.c b/servers/mfs/inode.c
index d18fc8bfb..ce529a1e0 100644
--- a/servers/mfs/inode.c
+++ b/servers/mfs/inode.c
@@ -45,7 +45,7 @@ int fs_putnode(void)
   rip = find_inode(fs_dev, (pino_t) fs_m_in.REQ_INODE_NR);
 
   if(!rip) {
-	  printf("%s:%d put_inode: inode #%u dev: %d not found\n", __FILE__,
+	  printf("%s:%d put_inode: inode #%u dev: %llx not found\n", __FILE__,
 		 __LINE__, (pino_t) fs_m_in.REQ_INODE_NR, fs_dev);
 	  panic("fs_putnode failed");
   }
diff --git a/servers/mfs/misc.c b/servers/mfs/misc.c
index 036d84cda..6b0a79d6d 100644
--- a/servers/mfs/misc.c
+++ b/servers/mfs/misc.c
@@ -38,7 +38,7 @@ int fs_flush()
 /* Flush the blocks of a device from the cache after writing any dirty blocks
  * to disk.
  */
-  dev_t dev = (dev_t) fs_m_in.REQ_DEV;
+  dev_t dev = fs_m_in.REQ_DEV;
   if(dev == fs_dev) return(EBUSY);
  
   lmfs_flushall();
@@ -60,7 +60,7 @@ int fs_new_driver(void)
   char label[sizeof(fs_dev_label)];
   int r;
 
-  dev = (dev_t) fs_m_in.REQ_DEV;
+  dev = fs_m_in.REQ_DEV;
   label_gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
   label_len = (size_t) fs_m_in.REQ_PATH_LEN;
 
diff --git a/servers/mfs/mount.c b/servers/mfs/mount.c
index efdcb299b..d4510bb06 100644
--- a/servers/mfs/mount.c
+++ b/servers/mfs/mount.c
@@ -24,7 +24,7 @@ int fs_readsuper()
   int r;
   int readonly, isroot;
 
-  fs_dev    = (dev_t) fs_m_in.REQ_DEV;
+  fs_dev    = fs_m_in.REQ_DEV;
   label_gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
   label_len = (size_t) fs_m_in.REQ_PATH_LEN;
   readonly  = (fs_m_in.REQ_FLAGS & REQ_RDONLY) ? 1 : 0;
@@ -76,7 +76,7 @@ int fs_readsuper()
 		panic("couldn't bdev_open after found unclean FS");
 		return(EINVAL);
   	}
-	printf("MFS: WARNING: FS 0x%x unclean, mounting readonly\n", fs_dev);
+	printf("MFS: WARNING: FS 0x%llx unclean, mounting readonly\n", fs_dev);
   }
   
   lmfs_set_blocksize(superblock.s_block_size, major(fs_dev));
diff --git a/servers/mfs/read.c b/servers/mfs/read.c
index 44c383254..c199b9803 100644
--- a/servers/mfs/read.c
+++ b/servers/mfs/read.c
@@ -160,7 +160,7 @@ int fs_breadwrite(void)
   
   r = OK;
 
-  target_dev = (dev_t) fs_m_in.REQ_DEV2;
+  target_dev = fs_m_in.REQ_DEV;
   
   /* Get the values from the request message */ 
   rw_flag = (fs_m_in.m_type == REQ_BREAD ? READING : WRITING);
diff --git a/servers/mfs/stadir.c b/servers/mfs/stadir.c
index 6b21d2952..a5da2ea57 100644
--- a/servers/mfs/stadir.c
+++ b/servers/mfs/stadir.c
@@ -70,7 +70,7 @@ static int stat_inode(
   statbuf.st_nlink = (nlink_t) rip->i_nlinks;
   statbuf.st_uid = rip->i_uid;
   statbuf.st_gid = rip->i_gid;
-  statbuf.st_rdev = (s ? (dev_t) rip->i_zone[0] : NO_DEV);
+  statbuf.st_rdev = (s ? (dev_t)rip->i_zone[0] : NO_DEV);
   statbuf.st_size = rip->i_size;
   statbuf.st_atime = rip->i_atime;
   statbuf.st_mtime = rip->i_mtime;
diff --git a/servers/pfs/inode.c b/servers/pfs/inode.c
index e81cad202..6d1b3d2f4 100644
--- a/servers/pfs/inode.c
+++ b/servers/pfs/inode.c
@@ -38,8 +38,8 @@ int fs_putnode(message *fs_m_in, message *fs_m_out)
   rip = find_inode( (pino_t) fs_m_in->REQ_INODE_NR);
 
   if(!rip) {
-	  printf("%s:%d put_inode: inode #%ld dev: %d not found\n", __FILE__,
-		 __LINE__, fs_m_in->REQ_INODE_NR, (dev_t) fs_m_in->REQ_DEV);
+	  printf("%s:%d put_inode: inode #%ld dev: %llx not found\n", __FILE__,
+		 __LINE__, fs_m_in->REQ_INODE_NR, fs_m_in->REQ_DEV);
 	  panic("fs_putnode failed");
   }
 
diff --git a/servers/pfs/open.c b/servers/pfs/open.c
index b7fc0a57f..4d8d202c3 100644
--- a/servers/pfs/open.c
+++ b/servers/pfs/open.c
@@ -20,7 +20,7 @@ int fs_newnode(message *fs_m_in, message *fs_m_out)
   uid = (uid_t) fs_m_in->REQ_UID;
   gid = (gid_t) fs_m_in->REQ_GID;
   bits = (pmode_t) fs_m_in->REQ_MODE;
-  dev = (dev_t) fs_m_in->REQ_DEV;
+  dev = fs_m_in->REQ_DEV;
 
   /* Try to allocate the inode */
   if( (rip = alloc_inode(dev, bits, uid, gid) ) == NULL) return(err_code);
diff --git a/servers/pfs/stadir.c b/servers/pfs/stadir.c
index c4bd7727a..e3909fec2 100644
--- a/servers/pfs/stadir.c
+++ b/servers/pfs/stadir.c
@@ -37,7 +37,7 @@ static int stat_inode(
   statbuf.st_nlink = rip->i_nlinks;
   statbuf.st_uid = rip->i_uid;
   statbuf.st_gid = (short int) rip->i_gid;
-  statbuf.st_rdev = (dev_t) (s ? rip->i_rdev : NO_DEV);
+  statbuf.st_rdev = (s ? rip->i_rdev : NO_DEV);
   statbuf.st_size = rip->i_size;
   if (!s)  statbuf.st_mode &= ~I_REGULAR;/* wipe out I_REGULAR bit for pipes */
   statbuf.st_atime = rip->i_atime;
diff --git a/servers/vfs/device.c b/servers/vfs/device.c
index 13d9435a3..071d4aa1a 100644
--- a/servers/vfs/device.c
+++ b/servers/vfs/device.c
@@ -505,7 +505,7 @@ int do_ioctl(void)
   }
 
   if (r == OK) {
-	dev = (dev_t) vp->v_sdev;
+	dev = vp->v_sdev;
 
 	if (S_ISBLK(vp->v_mode)) {
 		f->filp_ioctl_fp = fp;
diff --git a/servers/vfs/dmap.c b/servers/vfs/dmap.c
index 4bc5785ff..6a411661c 100644
--- a/servers/vfs/dmap.c
+++ b/servers/vfs/dmap.c
@@ -58,10 +58,8 @@ void unlock_dmap(struct dmap *dp)
 /*===========================================================================*
  *				map_driver		 		     *
  *===========================================================================*/
-static int map_driver(label, major, proc_nr_e)
-const char label[LABEL_MAX];	/* name of the driver */
-int major;			/* major number of the device */
-endpoint_t proc_nr_e;		/* process number of the driver */
+static int map_driver(const char label[LABEL_MAX], devmajor_t major,
+	endpoint_t proc_nr_e)
 {
 /* Add a new device driver mapping in the dmap table. If the proc_nr is set to
  * NONE, we're supposed to unmap it.
diff --git a/servers/vfs/filedes.c b/servers/vfs/filedes.c
index 81c40557e..0141de922 100644
--- a/servers/vfs/filedes.c
+++ b/servers/vfs/filedes.c
@@ -361,7 +361,7 @@ struct filp *f;
   if (f->filp_count - 1 == 0 && f->filp_mode != FILP_CLOSED) {
 	/* Check to see if the file is special. */
 	if (S_ISCHR(vp->v_mode) || S_ISBLK(vp->v_mode)) {
-		dev = (dev_t) vp->v_sdev;
+		dev = vp->v_sdev;
 		if (S_ISBLK(vp->v_mode))  {
 			lock_bsf();
 			if (vp->v_bfs_e == ROOT_FS_E) {
@@ -402,7 +402,7 @@ struct filp *f;
 	f->filp_mode = FILP_CLOSED;
 	f->filp_count = 0;
   } else if (f->filp_count < 0) {
-	panic("VFS: invalid filp count: %d ino %d/%llu", f->filp_count,
+	panic("VFS: invalid filp count: %d ino %llx/%llu", f->filp_count,
 	      vp->v_dev, vp->v_inode_nr);
   } else {
 	unlock_vnode(f->filp_vno);
diff --git a/servers/vfs/misc.c b/servers/vfs/misc.c
index e02648519..b78bf6a63 100644
--- a/servers/vfs/misc.c
+++ b/servers/vfs/misc.c
@@ -311,7 +311,7 @@ int dupvm(struct fproc *rfp, int pfd, int *vmfd, struct filp **newfilp)
 	assert(f->filp_vno->v_vmnt);
 
 	if (!S_ISREG(f->filp_vno->v_mode) && !S_ISBLK(f->filp_vno->v_mode)) {
-		printf("VFS: mmap regular/blockdev only; dev 0x%x ino %llu has mode 0%o\n",
+		printf("VFS: mmap regular/blockdev only; dev 0x%llx ino %llu has mode 0%o\n",
 			f->filp_vno->v_dev, f->filp_vno->v_inode_nr, f->filp_vno->v_mode);
 		unlock_filp(f);
 		return EINVAL;
@@ -648,7 +648,7 @@ static void free_proc(int flags)
 		if (rfilp->filp_mode == FILP_CLOSED) continue;
 		vp = rfilp->filp_vno;
 		if (!S_ISCHR(vp->v_mode)) continue;
-		if ((dev_t) vp->v_sdev != dev) continue;
+		if (vp->v_sdev != dev) continue;
 		lock_filp(rfilp, VNODE_READ);
 		(void) cdev_close(dev); /* Ignore any errors. */
 
diff --git a/servers/vfs/mount.c b/servers/vfs/mount.c
index 6569eb86d..a97d1ea01 100644
--- a/servers/vfs/mount.c
+++ b/servers/vfs/mount.c
@@ -178,7 +178,7 @@ char mount_label[LABEL_MAX] )
 	/* Get driver process' endpoint */
 	dp = &dmap[major(dev)];
 	if (dp->dmap_driver == NONE) {
-		printf("VFS: no driver for dev %d\n", dev);
+		printf("VFS: no driver for dev %llx\n", dev);
 		return(EINVAL);
 	}
 
@@ -466,7 +466,7 @@ int unmount(
   /* Find vmnt that is to be unmounted */
   for (vmp_i = &vmnt[0]; vmp_i < &vmnt[NR_MNTS]; ++vmp_i) {
 	  if (vmp_i->m_dev == dev) {
-		  if(vmp) panic("device mounted more than once: %d", dev);
+		  if(vmp) panic("device mounted more than once: %llx", dev);
 		  vmp = vmp_i;
 	  }
   }
@@ -565,7 +565,7 @@ void unmount_all(int force)
   /* Verify we succesfully unmounted all file systems */
   for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++) {
 	if (vmp->m_dev != NO_DEV) {
-		panic("vmp still mounted: %s %d %d\n", vmp->m_label,
+		panic("vmp still mounted: %s %d %llx\n", vmp->m_label,
 			vmp->m_fs_e, vmp->m_dev);
 	}
   }
diff --git a/servers/vfs/open.c b/servers/vfs/open.c
index 23db128b7..641224ebc 100644
--- a/servers/vfs/open.c
+++ b/servers/vfs/open.c
@@ -159,7 +159,7 @@ int common_open(char path[PATH_MAX], int oflags, mode_t omode)
 			break;
 		   case S_IFCHR:
 			/* Invoke the driver for special processing. */
-			dev = (dev_t) vp->v_sdev;
+			dev = vp->v_sdev;
 			/* TTY needs to know about the O_NOCTTY flag. */
 			r = cdev_open(dev, bits | (oflags & O_NOCTTY));
 			vp = filp->filp_vno;	/* Might be updated by
@@ -170,7 +170,7 @@ int common_open(char path[PATH_MAX], int oflags, mode_t omode)
 			lock_bsf();
 
 			/* Invoke the driver for special processing. */
-			dev = (dev_t) vp->v_sdev;
+			dev = vp->v_sdev;
 			r = bdev_open(dev, bits);
 			if (r != OK) {
 				unlock_bsf();
diff --git a/servers/vfs/pipe.c b/servers/vfs/pipe.c
index ab658d438..ce0909727 100644
--- a/servers/vfs/pipe.c
+++ b/servers/vfs/pipe.c
@@ -551,7 +551,7 @@ void unpause(void)
 			panic("process %d blocked on empty fd %d",
 				fp->fp_endpoint, fild);
 		}
-		dev = (dev_t) f->filp_vno->v_sdev;	/* device hung on */
+		dev = f->filp_vno->v_sdev;	/* device hung on */
 
 		status = cdev_cancel(dev);
 
diff --git a/servers/vfs/read.c b/servers/vfs/read.c
index c3c96d05f..36c91019b 100644
--- a/servers/vfs/read.c
+++ b/servers/vfs/read.c
@@ -167,12 +167,12 @@ int read_write(struct fproc *rfp, int rw_flag, struct filp *f,
 	if (vp->v_sdev == NO_DEV)
 		panic("VFS: read_write tries to access char dev NO_DEV");
 
-	dev = (dev_t) vp->v_sdev;
+	dev = vp->v_sdev;
 
 	r = cdev_io(op, dev, for_e, buf, position, size, f->filp_flags);
 	if (r >= 0) {
 		/* This should no longer happen: all calls are asynchronous. */
-		printf("VFS: I/O to device %x succeeded immediately!?\n", dev);
+		printf("VFS: I/O to device %llx succeeded immediately!?\n", dev);
 		cum_io = r;
 		position += r;
 		r = OK;
diff --git a/servers/vfs/request.c b/servers/vfs/request.c
index e6a91a780..df0aedf8f 100644
--- a/servers/vfs/request.c
+++ b/servers/vfs/request.c
@@ -50,7 +50,7 @@ int req_breadwrite(
 
   /* Fill in request message */
   m.m_type = rw_flag == READING ? REQ_BREAD : REQ_BWRITE;
-  m.REQ_DEV2 = dev;
+  m.REQ_DEV = dev;
   m.REQ_GRANT = grant_id;
   m.REQ_SEEK_POS_LO = ex64lo(pos);
   m.REQ_SEEK_POS_HI = ex64hi(pos);
@@ -79,7 +79,7 @@ int req_bpeek(endpoint_t fs_e, dev_t dev, off_t pos, unsigned int num_of_bytes)
 
   /* Fill in request message */
   m.m_type = REQ_BPEEK;
-  m.REQ_DEV2 = dev;
+  m.REQ_DEV = dev;
   m.REQ_SEEK_POS_LO = ex64lo(pos);
   m.REQ_SEEK_POS_HI = ex64hi(pos);
   m.REQ_NBYTES = num_of_bytes;
diff --git a/servers/vfs/select.c b/servers/vfs/select.c
index fc8b189d4..537e4d879 100644
--- a/servers/vfs/select.c
+++ b/servers/vfs/select.c
@@ -805,7 +805,7 @@ int status;
 		/* This should never happen. The driver may be misbehaving.
 		 * For now we assume that the reply we want will arrive later..
 		 */
-		printf("VFS (%s:%d): expected reply from dev %d not %d\n",
+		printf("VFS (%s:%d): expected reply from dev %llx not %llx\n",
 			__FILE__, __LINE__, vp->v_sdev, dev);
 		return;
 	}
diff --git a/servers/vfs/stadir.c b/servers/vfs/stadir.c
index f864dbf27..971fc6830 100644
--- a/servers/vfs/stadir.c
+++ b/servers/vfs/stadir.c
@@ -276,9 +276,9 @@ static int fill_statvfs(struct vmnt *vmp, endpoint_t endpt, vir_bytes buf_addr,
   if (vmp->m_flags & VMNT_READONLY)
 	buf.f_flag |= ST_RDONLY;
 
-  buf.f_fsid = vmp->m_dev;
-  buf.f_fsidx.__fsid_val[0] = 0;
-  buf.f_fsidx.__fsid_val[1] = vmp->m_dev;
+  buf.f_fsid = (unsigned long)vmp->m_dev;
+  buf.f_fsidx.__fsid_val[0] = (long)vmp->m_dev; /* This is what is done on NetBSD */
+  buf.f_fsidx.__fsid_val[1] = 0; /* Here they convert the FS type name into a number. */
 
   strlcpy(buf.f_fstypename, vmp->m_fstype, sizeof(buf.f_fstypename));
   strlcpy(buf.f_mntonname, vmp->m_mount_path, sizeof(buf.f_mntonname));
diff --git a/servers/vfs/vmnt.c b/servers/vfs/vmnt.c
index b7e3d6567..7e17d204f 100644
--- a/servers/vfs/vmnt.c
+++ b/servers/vfs/vmnt.c
@@ -49,7 +49,7 @@ void check_vmnt_locks()
   for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++)
 	if (is_vmnt_locked(vmp)) {
 		count++;
-		printf("vmnt %p is %s, fs_e=%d dev=%d\n", vmp, (tll_islocked(&vmp->m_lock) ? "locked":"pending locked"), vmp->m_fs_e, vmp->m_dev);
+		printf("vmnt %p is %s, fs_e=%d dev=%llx\n", vmp, (tll_islocked(&vmp->m_lock) ? "locked":"pending locked"), vmp->m_fs_e, vmp->m_dev);
 	}
 
   if (count) panic("%d locked vmnts\n", count);
diff --git a/sys/sys/types.h b/sys/sys/types.h
index 140eebcc1..18c557b24 100644
--- a/sys/sys/types.h
+++ b/sys/sys/types.h
@@ -183,9 +183,7 @@ typedef	__daddr_t	daddr_t;	/* disk address */
 typedef	int64_t		daddr_t;	/* disk address */
 #endif
 
-#if defined(__minix) /* LSC: Wait until bigger message to enlarge the data type. */
-typedef	uint32_t	dev_t;		/* device number */
-#endif /* defined(__minix) */
+typedef	uint64_t	dev_t;		/* device number */
 typedef	uint32_t	fixpt_t;	/* fixed point number */
 
 #ifndef	gid_t
diff --git a/test/blocktest/blocktest.c b/test/blocktest/blocktest.c
index 70c49431d..995bd9a39 100644
--- a/test/blocktest/blocktest.c
+++ b/test/blocktest/blocktest.c
@@ -29,7 +29,7 @@ typedef struct {
 } result_t;
 
 static char driver_label[32] = "";	/* driver DS label */
-static dev_t driver_minor = -1;	/* driver's partition minor to use */
+static devminor_t driver_minor = -1;	/* driver's partition minor to use */
 static endpoint_t driver_endpt;	/* driver endpoint */
 
 static int may_write = FALSE;		/* may we write to the device? */
diff --git a/test/test72.c b/test/test72.c
index 4407fc239..ba48c2170 100644
--- a/test/test72.c
+++ b/test/test72.c
@@ -252,19 +252,19 @@ u32_t sqrt_approx(u32_t v)
 	return (u32_t) sqrt(v);
 }
 
-int vm_set_cacheblock(void *block, u32_t dev, u64_t dev_offset,
+int vm_set_cacheblock(void *block, dev_t dev, u64_t dev_offset,
         u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize)
 {
 	return ENOSYS;
 }
 
-void *vm_map_cacheblock(u32_t dev, u64_t dev_offset,
+void *vm_map_cacheblock(dev_t dev, u64_t dev_offset,
         u64_t ino, u64_t ino_offset, u32_t *flags, int blocksize)
 {
 	return MAP_FAILED;
 }
 
-int vm_clear_cache(u32_t dev)
+int vm_clear_cache(dev_t dev)
 {
 	return 0;
 }