diff --git a/src/libpriv/rpmostree-kernel.c b/src/libpriv/rpmostree-kernel.c
index 579beacf14..38f88e8255 100644
--- a/src/libpriv/rpmostree-kernel.c
+++ b/src/libpriv/rpmostree-kernel.c
@@ -493,7 +493,7 @@ rpmostree_run_dracut (int     rootfs_dfd,
                                       O_RDWR | O_CLOEXEC,
                                       &tmpf, error))
     goto out;
-  if (glnx_loop_write (tmpf.fd, rpmostree_dracut_wrapper, sizeof (rpmostree_dracut_wrapper)) < 0
+  if (glnx_loop_write (tmpf.fd, rpmostree_dracut_wrapper, strlen (rpmostree_dracut_wrapper)) < 0
       || fchmod (tmpf.fd, 0755) < 0)
     {
       glnx_set_error_from_errno (error);