diff --git a/src/command/config/update/v1.rs b/src/command/config/update/v1.rs
index 5cfd74f..7f95915 100644
--- a/src/command/config/update/v1.rs
+++ b/src/command/config/update/v1.rs
@@ -1,15 +1,16 @@
 //! `config update v1` subcommand
 //! <https://firefish.dev/firefish/firefish/-/issues/10947>
 
-use crate::config::{
-    client, server, Revision, CLIENT_CONFIG_PATH, OLD_CONFIG_PATH, SERVER_CONFIG_PATH,
+use crate::{
+    command::config::{read_file_as_string, ReadError},
+    config::{client, server, Revision, CLIENT_CONFIG_PATH, OLD_CONFIG_PATH, SERVER_CONFIG_PATH},
 };
 use color_print::cprintln;
 use sqlx::{postgres::PgConnectOptions, ConnectOptions};
 use std::{
     collections::HashMap,
     fs,
-    io::{self, Read, Write},
+    io::{self, Write},
     path::Path,
 };
 use url::Url;
@@ -34,7 +35,7 @@ pub(crate) enum Error {
 #[derive(thiserror::Error, Debug)]
 pub(crate) enum ReadYamlConfigError {
     #[error(transparent)]
-    ReadFile(#[from] io::Error),
+    ReadFile(#[from] ReadError),
     #[error(transparent)]
     Yaml(#[from] yaml_rust::ScanError),
     #[error("invalid config ({0})")]
@@ -57,12 +58,7 @@ pub(crate) enum WriteTomlConfigError {
 }
 
 fn read_default_yml() -> Result<HashMap<String, Yaml>, ReadYamlConfigError> {
-    let mut default_yml = fs::File::open(OLD_CONFIG_PATH)?;
-
-    let mut buffer = String::new();
-    default_yml.read_to_string(&mut buffer)?;
-
-    let content = YamlLoader::load_from_str(&buffer)?;
+    let content = YamlLoader::load_from_str(&read_file_as_string(OLD_CONFIG_PATH)?)?;
 
     if content.is_empty() {
         return Err(ReadYamlConfigError::InvalidConfig(