diff --git a/src/clean_url.js b/src/clean_url.js
index 9581aeb9..21704643 100644
--- a/src/clean_url.js
+++ b/src/clean_url.js
@@ -1,3 +1,5 @@
+'use strict'
+
 import { createInterface } from 'node:readline'
 
 for await (const line of createInterface({ input: process.stdin, terminal: false })) {
diff --git a/src/ids.js b/src/ids.js
index 2f7c3ebc..73bf09e9 100644
--- a/src/ids.js
+++ b/src/ids.js
@@ -1,3 +1,5 @@
+'use strict'
+
 import { createWriteStream } from 'node:fs'
 import { open } from 'node:fs/promises'