diff --git a/packages/rete/src/aggregate.ts b/packages/rete/src/aggregate.ts
index 13dc449..f4fd220 100644
--- a/packages/rete/src/aggregate.ts
+++ b/packages/rete/src/aggregate.ts
@@ -62,7 +62,7 @@
  * ExistentialNode upstream.
  */
 import { Token, type Bindings } from "./beta.js";
-import type { EntityId } from "./schema.js";
+import { asEntityId } from "./schema.js";
 import type { AttrKey, FactValue } from "./wm.js";
 
 /** Supported aggregator kinds. Extending this list requires a new case in
@@ -85,7 +85,7 @@ type DeactivateListener = (token: Token) => void;
  * `schema.ts`), so there is no risk of collision.
  */
 const AGG_FACT = {
-  id: -1 as unknown as EntityId,
+  id: asEntityId(-1),
   attr: "__agg__" as AttrKey,
   value: null as FactValue,
 } as const;