diff --git a/src/bot.ts b/src/bot.ts
index 8db771d..46820af 100644
--- a/src/bot.ts
+++ b/src/bot.ts
@@ -32,7 +32,7 @@ export class ChannelBot {
     process.once('SIGINT', () => this.bot.stop('SIGINT'));
     process.once('SIGTERM', () => this.bot.stop('SIGTERM'));
 
-    this.bot.on('chat_member', this.handleChatMemberUpdate.bind(this));
+    this.bot.on('chat_member', (ctx) => this.handleChatMemberUpdate(ctx));
 
     this.bot.launch(
       {