diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 358573c..0cc5e90 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -119,7 +119,7 @@ static int	closefp(struct filedesc *fdp, int fd, struct file *fp,
 static int	do_dup(struct thread *td, int flags, int old, int new,
     register_t *retval);
 static int	fd_first_free(struct filedesc *, int, int);
-static int	fd_last_used(struct filedesc *, int, int);
+static int	fd_last_used(struct filedesc *, int);
 static void	fdgrowtable(struct filedesc *, int);
 static void	fdunused(struct filedesc *fdp, int fd);
 static void	fdused(struct filedesc *fdp, int fd);
@@ -216,19 +216,16 @@ fd_first_free(struct filedesc *fdp, int low, int size)
 }
 
 /*
- * Find the highest non-zero bit in the given bitmap, starting at low and
+ * Find the highest non-zero bit in the given bitmap, starting at 0 and
  * not exceeding size - 1.
  */
 static int
-fd_last_used(struct filedesc *fdp, int low, int size)
+fd_last_used(struct filedesc *fdp, int size)
 {
 	NDSLOTTYPE *map = fdp->fd_map;
 	NDSLOTTYPE mask;
 	int off, minoff;
 
-	if (low >= size)
-		return (-1);
-
 	off = NDSLOT(size);
 	if (size % NDENTRIES) {
 		mask = ~(~(NDSLOTTYPE)0 << (size % NDENTRIES));
@@ -236,10 +233,10 @@ fd_last_used(struct filedesc *fdp, int low, int size)
 			return (off * NDENTRIES + flsl(mask) - 1);
 		--off;
 	}
-	for (minoff = NDSLOT(low); off >= minoff; --off)
+	for (minoff = NDSLOT(0); off >= minoff; --off)
 		if (map[off] != 0)
 			return (off * NDENTRIES + flsl(map[off]) - 1);
-	return (low - 1);
+	return (-1);
 }
 
 static int
@@ -285,7 +282,7 @@ fdunused(struct filedesc *fdp, int fd)
 	if (fd < fdp->fd_freefile)
 		fdp->fd_freefile = fd;
 	if (fd == fdp->fd_lastfile)
-		fdp->fd_lastfile = fd_last_used(fdp, 0, fd);
+		fdp->fd_lastfile = fd_last_used(fdp, fd);
 }
 
 /*