diff --git a/typings/index.d.ts b/typings/index.d.ts
index 0170ebf4c..7f7b59927 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -146,7 +146,7 @@ declare module 'discord.js' {
 		public on(event: 'typingStart' | 'typingStop', listener: (channel: Channel, user: User) => void): this;
 		public on(event: 'userNoteUpdate', listener: (user: UserResolvable, oldNote: string, newNote: string) => void): this;
 		public on(event: 'userUpdate', listener: (oldUser: User, newUser: User) => void): this;
-		public once(event: 'voiceStateUpdate', listener: (oldState: VoiceState | undefined, newState: VoiceState) => void): this;
+		public once(event: 'voiceStateUpdate', listener: (oldState: VoiceState, newState: VoiceState) => void): this;
 		public on(event: string, listener: Function): this;
 
 		public once(event: 'channelCreate' | 'channelDelete', listener: (channel: Channel) => void): this;
@@ -180,7 +180,7 @@ declare module 'discord.js' {
 		public once(event: 'typingStart' | 'typingStop', listener: (channel: Channel, user: User) => void): this;
 		public once(event: 'userNoteUpdate', listener: (user: UserResolvable, oldNote: string, newNote: string) => void): this;
 		public once(event: 'userUpdate', listener: (oldUser: User, newUser: User) => void): this;
-		public once(event: 'voiceStateUpdate', listener: (oldState: VoiceState | undefined, newState: VoiceState) => void): this;
+		public once(event: 'voiceStateUpdate', listener: (oldState: VoiceState, newState: VoiceState) => void): this;
 		public once(event: string, listener: Function): this;
 	}