diff --git a/src/command.ts b/src/command.ts
index 989a2df1..7b6874e5 100644
--- a/src/command.ts
+++ b/src/command.ts
@@ -2,7 +2,7 @@ import {IConfig} from './config'
 import {IPlugin} from './plugin'
 
 export interface ICachedCommand {
-  id?: string
+  id: string
   base: string
   hidden: boolean
   aliases: string[]