Index: sys/kern/vfs_subr.c
===================================================================
--- sys/kern/vfs_subr.c
+++ sys/kern/vfs_subr.c
@@ -267,7 +267,7 @@
  * XXX desiredvnodes is historical cruft and should not exist.
  */
 int desiredvnodes;
-SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW,
+SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RDTUN,
     &desiredvnodes, 0, "Maximum number of vnodes");
 SYSCTL_ULONG(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
     &wantfreevnodes, 0, "Minimum number of vnodes (legacy)");