diff --git a/src/index.ts b/src/index.ts
index 8a7317a..86a11ee 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -46,6 +46,7 @@ const MAIN_ARGS = usage(`Usage: $0 <mode> [options]`)
   })
   .option('mode', {
     alias: ['m'],
+    choices: ['check', 'fix'],
     default: 'check',
     type: 'string',
   })