--- src/sys/kern/vfs_syscalls.c	2007/05/09 00:53:34	1.116
+++ src/sys/kern/vfs_syscalls.c	2007/06/26 20:39:33	1.117
@@ -926,10 +926,14 @@ sys_mountctl(struct mountctl_args *uap)
 	/*
 	 * Validate the descriptor
 	 */
-	fp = holdfp(p->p_fd, uap->fd, -1);
-	if (fp == NULL) {
-		error = EBADF;
-		goto done;
+	if (uap->fd >= 0) {
+		fp = holdfp(p->p_fd, uap->fd, -1);
+		if (fp == NULL) {
+			error = EBADF;
+			goto done;
+		}
+	} else {
+		fp = NULL;
 	}
 
 	/*