diff --git a/include/minix/callnr.h b/include/minix/callnr.h
index c70f2e257..5c91e70e4 100644
--- a/include/minix/callnr.h
+++ b/include/minix/callnr.h
@@ -232,12 +232,6 @@
 
 #define NR_VFS_CALLS		49	/* highest number from base plus one */
 
-/* Field names for the umount(2) call. */
-#define VFS_UMOUNT_NAME		m1_p1	/* char * */
-#define VFS_UMOUNT_NAMELEN	m1_i1	/* size_t */
-#define VFS_UMOUNT_LABEL	m1_p2	/* char * */
-#define VFS_UMOUNT_LABELLEN	m1_i2	/* size_t */
-
 /* Field names for the ioctl(2) call. */
 #define VFS_IOCTL_FD		m2_i1	/* int */
 #define VFS_IOCTL_REQ		m2_i3	/* unsigned long */
diff --git a/include/minix/ipc.h b/include/minix/ipc.h
index 8d53d647c..5d56726ee 100644
--- a/include/minix/ipc.h
+++ b/include/minix/ipc.h
@@ -192,6 +192,16 @@ typedef struct {
 } mess_lc_vfs_statvfs1;
 _ASSERT_MSG_SIZE(mess_lc_vfs_statvfs1);
 
+typedef struct {
+	vir_bytes name;
+	size_t namelen;
+	vir_bytes label;
+	size_t labellen;
+
+	uint8_t padding[40];
+} mess_lc_vfs_umount;
+_ASSERT_MSG_SIZE(mess_lc_vfs_umount);
+
 typedef struct {
 	dev_t device;
 	off_t seek_pos;
@@ -647,6 +657,7 @@ typedef struct {
 		mess_lc_vfs_mount	m_lc_vfs_mount;
 		mess_lc_vfs_select	m_lc_vfs_select;
 		mess_lc_vfs_statvfs1	m_lc_vfs_statvfs1;
+		mess_lc_vfs_umount	m_lc_vfs_umount;
 
 		mess_vfs_fs_breadwrite	m_vfs_fs_breadwrite;
 		mess_vfs_fs_chmod	m_vfs_fs_chmod;
diff --git a/lib/libc/sys-minix/mount.c b/lib/libc/sys-minix/mount.c
index 1a2dd6902..6e2703d46 100644
--- a/lib/libc/sys-minix/mount.c
+++ b/lib/libc/sys-minix/mount.c
@@ -172,10 +172,10 @@ int minix_umount(const char *name, int srvflags)
   int r;
 
   memset(&m, 0, sizeof(m));
-  m.VFS_UMOUNT_NAME = __UNCONST(name);
-  m.VFS_UMOUNT_NAMELEN = strlen(name) + 1;
-  m.VFS_UMOUNT_LABEL = label;
-  m.VFS_UMOUNT_LABELLEN = sizeof(label);
+  m.m_lc_vfs_umount.name = (vir_bytes)name;
+  m.m_lc_vfs_umount.namelen = strlen(name) + 1;
+  m.m_lc_vfs_umount.label = (vir_bytes)label;
+  m.m_lc_vfs_umount.labellen = sizeof(label);
   r = _syscall(VFS_PROC_NR, VFS_UMOUNT, &m);
 
   /* don't shut down the driver when exist flag is set */	
diff --git a/servers/vfs/mount.c b/servers/vfs/mount.c
index 59ddf547e..350dfc95c 100644
--- a/servers/vfs/mount.c
+++ b/servers/vfs/mount.c
@@ -425,10 +425,10 @@ int do_umount(void)
   vir_bytes vname, label_addr;
   size_t vname_length, label_len;
 
-  vname = (vir_bytes) job_m_in.VFS_UMOUNT_NAME;
-  vname_length = (size_t) job_m_in.VFS_UMOUNT_NAMELEN;
-  label_addr = (vir_bytes) job_m_in.VFS_UMOUNT_LABEL;
-  label_len = (size_t) job_m_in.VFS_UMOUNT_LABELLEN;
+  vname = job_m_in.m_lc_vfs_umount.name;
+  vname_length = job_m_in.m_lc_vfs_umount.namelen;
+  label_addr = job_m_in.m_lc_vfs_umount.label;
+  label_len = job_m_in.m_lc_vfs_umount.labellen;
 
   /* Only the super-user may do umount. */
   if (!super_user) return(EPERM);