diff --git a/jecs.d.ts b/jecs.d.ts
index 09f959b..959d08b 100644
--- a/jecs.d.ts
+++ b/jecs.d.ts
@@ -246,7 +246,7 @@ export function component<T>(): Entity<T>;
 export function tag<T>(): Entity<T>;
 
 // note: original types had id: Entity, id: Id<T>, which does not work with TS.
-export function meta<T>(e: Entity, id: Id<T>, value: T): Entity<T>
+export function meta<T>(e: Entity, id: Id<T>, value?: T): Entity<T>
 
 export function is_tag<T>(world: World, id: Id<T>): boolean;