diff --git a/nodejs/lancedb/arrow.ts b/nodejs/lancedb/arrow.ts
index 710889d5e..71e3abaae 100644
--- a/nodejs/lancedb/arrow.ts
+++ b/nodejs/lancedb/arrow.ts
@@ -79,7 +79,7 @@ export type FieldLike =
  * type of this one even though it is structurally identical. Inputs that only
  * need to be sanitized accept this looser shape instead.
  */
-export type DataTypeLike = DataType | { readonly typeId: unknown };
+export type DataTypeLike = DataType | { readonly typeId: number };
 
 /**
  * Create an Arrow field backed by LanceDB's JSON extension type.