diff --git a/sh/id.sh b/sh/id.sh
new file mode 100644
index 0000000..a78a49d
--- /dev/null
+++ b/sh/id.sh
@@ -0,0 +1,9 @@
+# id
+
+# check if current user is root
+#| id
+rwx_id_root() {
+	local user_id
+	user_id="$(id -u)"
+	[ "${user_id}" -eq 0 ] || return 1
+}
diff --git a/sh/tty/tmux.sh b/sh/tty/tmux.sh
index 4557ecb..ccae525 100644
--- a/sh/tty/tmux.sh
+++ b/sh/tty/tmux.sh
@@ -230,7 +230,7 @@ ${RWX_TMUX_BORDER_BACKGROUND}#{?window_zoomed_flag,\
 #/ tmux_setup
 rwx_tmux_setup() {
 	local file script space
-	if rwx_root; then
+	if rwx_id_root; then
 		file="/etc/tmux.conf"
 		script="/etc/tmux.sh"
 	else
diff --git a/sh/util.sh b/sh/util.sh
index b396901..f622b2c 100644
--- a/sh/util.sh
+++ b/sh/util.sh
@@ -35,12 +35,6 @@ rwx_remove() {
 		"${@}"
 }
 
-rwx_root() {
-	local user_id
-	user_id="$(id --user)"
-	[ "${user_id}" -eq 0 ] || return 1
-}
-
 rwx_warn_wipe() {
 	local tmp
 	rwx_list_block