diff -dur a/tmpfs/node.c b/tmpfs/node.c
--- a/tmpfs/node.c	2010-05-19 16:01:43.000000000 +0200
+++ b/tmpfs/node.c	2010-05-19 16:04:27.000000000 +0200
@@ -61,8 +61,10 @@
   switch (np->dn->type)
     {
     case DT_REG:
-      if (np->dn->u.reg.memobj != MACH_PORT_NULL)
+      if (np->dn->u.reg.memobj != MACH_PORT_NULL) {
+	vm_deallocate (mach_task_self (), np->dn->u.reg.memref, 4096);
 	mach_port_deallocate (mach_task_self (), np->dn->u.reg.memobj);
+      }
       break;
     case DT_DIR:
       assert (np->dn->u.dir.entries == 0);
@@ -500,6 +502,13 @@
 	 past the specified size of the file.  */
       err = default_pager_object_set_size (np->dn->u.reg.memobj,
 					   np->allocsize);
+      assert_perror (err);
+
+      /* XXX we need to keep a reference to the object, or GNU Mach
+	 will terminate it when we release the map. */
+      vm_map (mach_task_self (), &np->dn->u.reg.memref, 4096, 0, 1,
+	      np->dn->u.reg.memobj, 0, 0, VM_PROT_NONE, VM_PROT_NONE,
+	      VM_INHERIT_NONE);
     }
 
   /* XXX always writable */
diff -dur a/tmpfs/tmpfs.h b/tmpfs/tmpfs.h
--- a/tmpfs/tmpfs.h	2010-05-19 15:51:44.000000000 +0200
+++ b/tmpfs/tmpfs.h	2010-05-19 16:00:03.000000000 +0200
@@ -47,6 +47,7 @@
     struct
     {
       mach_port_t memobj;
+      vm_address_t memref;
       unsigned int allocpages;	/* largest size while memobj was live */
     } reg;
     struct