diff --git a/packages/core/src/command/command.ts b/packages/core/src/command/command.ts
index 2aa39d1c5..16be10af1 100644
--- a/packages/core/src/command/command.ts
+++ b/packages/core/src/command/command.ts
@@ -98,8 +98,12 @@ export class Command<
     }
   }
 
+  static normalize(name: string) {
+    return name.toLowerCase().replace(/_/g, '-')
+  }
+
   private _registerAlias(name: string, prepend = false, options: Command.Alias = {}) {
-    name = name.toLowerCase()
+    name = Command.normalize(name)
     if (name.startsWith('.')) name = this.parent.name + name
 
     // check global
diff --git a/packages/core/src/command/index.ts b/packages/core/src/command/index.ts
index 7a072f142..d330e672c 100644
--- a/packages/core/src/command/index.ts
+++ b/packages/core/src/command/index.ts
@@ -269,7 +269,7 @@ export class Commander {
 
   _resolve(key: string) {
     if (!key) return {}
-    const segments = key.toLowerCase().split('.')
+    const segments = Command.normalize(key).split('.')
     let i = 1, name = segments[0], command: Command
     while ((command = this.get(name)) && i < segments.length) {
       name = command.name + '.' + segments[i++]
@@ -325,7 +325,7 @@ export class Commander {
   command(def: string, ...args: [Command.Config?] | [string, Command.Config?]) {
     const desc = typeof args[0] === 'string' ? args.shift() as string : ''
     const config = args[0] as Command.Config
-    const path = def.split(' ', 1)[0].toLowerCase()
+    const path = Command.normalize(def.split(' ', 1)[0])
     const decl = def.slice(path.length)
     const segments = path.split(/(?=[./])/g)