diff --git a/sdk_container/src/third_party/coreos-overlay/sys-kernel/bootengine/bootengine-9999.ebuild b/sdk_container/src/third_party/coreos-overlay/sys-kernel/bootengine/bootengine-9999.ebuild
index 628df332ec..5833dd5a0b 100644
--- a/sdk_container/src/third_party/coreos-overlay/sys-kernel/bootengine/bootengine-9999.ebuild
+++ b/sdk_container/src/third_party/coreos-overlay/sys-kernel/bootengine/bootengine-9999.ebuild
@@ -58,7 +58,7 @@ src_install() {
 # cpio image in pkg_postinst() where we are free to mount filesystems, chroot,
 # and other fun stuff.
 pkg_postinst() {
-	if [[ -n "${ROOT}" ]]; then
+	if [[ "${ROOT:-/}" != / ]]; then
 		${ROOT}/usr/sbin/update-bootengine -m -c ${ROOT} || die
 	else
 		update-bootengine || die