diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 97ab886ec55..aa5322a1893 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -5053,6 +5053,7 @@ vfs_read_dirent(struct vop_readdir_args *ap, struct dirent *dp, off_t off)
 	*ap->a_cookies = realloc(*ap->a_cookies,
 	    (*ap->a_ncookies + 1) * sizeof(u_long), M_TEMP, M_WAITOK | M_ZERO);
 	(*ap->a_cookies)[*ap->a_ncookies] = off;
+	*ap->a_ncookies += 1;
 	return (0);
 }