diff --git a/servers/vfs/main.c b/servers/vfs/main.c
index bfd62da0f..49a8233e7 100644
--- a/servers/vfs/main.c
+++ b/servers/vfs/main.c
@@ -222,8 +222,8 @@ PRIVATE void fs_init()
   int s;
 
   /* Clear endpoint field */
-  last_login_fs_e = 0;
-  mount_m_in.m1_p3 = 0;
+  last_login_fs_e = NONE;
+  mount_m_in.m1_p3 = (char *) NONE;
 
   /* Initialize the process table with help of the process manager messages. 
    * Expect one message for each system process with its slot number and pid. 
@@ -313,7 +313,7 @@ PRIVATE void init_root()
 		  panic(__FILE__, "Error receiving login request from root filesystem\n", ROOT_FS_E);
 	  }
   }
-  last_login_fs_e = 0;
+  last_login_fs_e = NONE;
   
   /* Initialize vmnt table */
   for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
diff --git a/servers/vfs/mount.c b/servers/vfs/mount.c
index 769926ea3..f337e3bef 100644
--- a/servers/vfs/mount.c
+++ b/servers/vfs/mount.c
@@ -72,10 +72,19 @@ PUBLIC int do_mount()
 {
   endpoint_t fs_e; 
   int r;
+
+  /* Only the super-user may do MOUNT. */
+  if (!super_user) return(EPERM);
 	
   /* FS process' endpoint number */ 
   fs_e = (unsigned long)m_in.m1_p3;
 
+  /* Sanity check on process number. */
+  if(fs_e <= 0) {
+	printf("vfs: warning: got process number %d for mount call.\n", fs_e);
+	return EINVAL;
+  }
+
   /* Do the actual job */
   r = mount_fs(fs_e);
 
@@ -123,10 +132,10 @@ PRIVATE int mount_fs(endpoint_t fs_e)
   
   /* Mount request got after FS login or 
    * FS login arrived after a suspended mount */
-  last_login_fs_e = 0;
+  last_login_fs_e = NONE;
   
   /* Clear endpoint field */
-  mount_m_in.m1_p3 = 0;
+  mount_m_in.m1_p3 = (char *) NONE;
 
   /* If 'name' is not for a block special file, return error. */
   if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
@@ -466,18 +475,23 @@ PUBLIC int unmount(dev)
 Dev_t dev;
 {
   struct vnode *vp;
-  struct vmnt *vmp;
+  struct vmnt *vmp_i = NULL, *vmp = NULL;
   struct dmap *dp;
   int count, r;
   int fs_e;
 
   /* Find vmnt */
-  for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
-      if (vmp->m_dev == dev) break;
-      else if (vmp == &vmnt[NR_MNTS])
-          return EINVAL;
+  for (vmp_i = &vmnt[0]; vmp_i < &vmnt[NR_MNTS]; ++vmp_i) {
+      if (vmp->m_dev == dev) {
+	if(vmp) panic(__FILE__, "device mounted more than once", dev);
+	vmp = vmp_i;
+      }
   }
 
+  /* Device mounted? */
+  if(!vmp)
+	return EINVAL;
+
   /* See if the mounted device is busy.  Only 1 vnode using it should be
    * open -- the root vnode -- and that inode only 1 time.
    */
@@ -496,6 +510,8 @@ Dev_t dev;
   vnode_clean_refs(vmp->m_root_node);
 
   /* Request FS the unmount */
+  if(vmp->m_fs_e <= 0)
+	panic(__FILE__, "unmount: strange fs endpoint", vmp->m_fs_e);
   if ((r = req_unmount(vmp->m_fs_e)) != OK) return r;
 
   /* Close the device the file system lives on. */
@@ -541,8 +557,8 @@ Dev_t dev;
   vmp->m_root_node = NIL_VNODE;
   vmp->m_mounted_on = NIL_VNODE;
   vmp->m_dev = NO_DEV;
-  vmp->m_fs_e = 0;
-  vmp->m_driver_e = 0;
+  vmp->m_fs_e = NONE;
+  vmp->m_driver_e = NONE;
 
   /* Ask RS to bring down FS */
   if (-1 == fs_exit(fs_e)) {
diff --git a/servers/vfs/open.c b/servers/vfs/open.c
index 13a49de5c..ae8756299 100644
--- a/servers/vfs/open.c
+++ b/servers/vfs/open.c
@@ -150,7 +150,7 @@ PRIVATE int common_open(register int oflags, mode_t omode)
 		r= OK;
 	else
 	{
-		printf("common_open: / in pathrem");
+		printf("common_open: / in pathrem\n");
 	}
   }
 
diff --git a/servers/vfs/proto.h b/servers/vfs/proto.h
index 67aaf73ac..bfcca929f 100644
--- a/servers/vfs/proto.h
+++ b/servers/vfs/proto.h
@@ -133,7 +133,6 @@ _PROTOTYPE( int do_getdents, (void)					);
 _PROTOTYPE( int read_write, (int rw_flag)				);
 
 /* request.c */
-_PROTOTYPE( int fs_sendrec, (endpoint_t fs_e, message *reqm)            );
 _PROTOTYPE( int req_getnode, (node_req_t *req, node_details_t *res)     );
 _PROTOTYPE( int req_putnode, (int fs_e, ino_t inode_nr, int count)	);
 _PROTOTYPE( int req_open, (open_req_t *req, node_details_t *res)        ); 
diff --git a/servers/vfs/request.c b/servers/vfs/request.c
index b41ea8746..4e2d739f3 100644
--- a/servers/vfs/request.c
+++ b/servers/vfs/request.c
@@ -28,6 +28,7 @@
 #include "vnode.h"
 #include "param.h"
 
+FORWARD _PROTOTYPE(int fs_sendrec, (endpoint_t fs_e, message *reqm));
 
 /*===========================================================================*
  *				req_getnode				     *
@@ -954,7 +955,7 @@ _t *res;
 /*===========================================================================*
  *				fs_sendrec				     *
  *===========================================================================*/
-PUBLIC int fs_sendrec(endpoint_t fs_e, message *reqm)
+PRIVATE int fs_sendrec(endpoint_t fs_e, message *reqm)
 {
 /* This is the low level function that sends requests to FS processes.
  * It also handles driver recovery mechanism and reissuing the