diff --git a/setup-disk.in b/setup-disk.in
index 92627d9f428a98b019d3ff86c9aa44f0636e0d6a..023974e14902b0e5d60b0cd0f37c48091f07a568 100644
--- a/setup-disk.in
+++ b/setup-disk.in
@@ -286,6 +286,7 @@ install_mounted_root() {
 
 	# generate update-extlinux.conf
 	root=$(uuid_or_device $rootdev)
+	kernel_opts="$kernel_opts rootfstype=$root_fs"
 	if is_vmware; then
 		kernel_opts="pax_nouderef $kernel_opts"
 	fi