diff --git a/packages/transducers/src/func/hex.ts b/packages/transducers/src/func/hex.ts
index d5228cf139..747161cedc 100644
--- a/packages/transducers/src/func/hex.ts
+++ b/packages/transducers/src/func/hex.ts
@@ -6,4 +6,4 @@ import { radix } from "@thi.ng/strings/radix";
  * @param digits
  * @param prefix
  */
-export const hex = (digits = 2, prefix = "") => radix(16, digits, prefix);
+export const hex = (digits = 2, prefix = ""): (x: number) => string => radix(16, digits, prefix);