diff --git a/actor.ts b/actor.ts
index 28cf806..083e5a2 100644
--- a/actor.ts
+++ b/actor.ts
@@ -41,7 +41,7 @@ export const CDict = Record.makeConstructor<{}, Ref>()(
     _CDict, []);
 
 export type ConstructorSpec =
-    | Record<typeof _CRec, [string, number], Ref>
+    | Record<typeof _CRec, [Assertion, number], Ref>
     | Record<typeof _CArr, [number], Ref>
     | Record<typeof _CDict, [], Ref>;