diff --git a/crypto/_fnv/index.ts b/crypto/_fnv/mod.ts
similarity index 86%
rename from crypto/_fnv/index.ts
rename to crypto/_fnv/mod.ts
index 1fad4d2c2709..f8be267a33ab 100644
--- a/crypto/_fnv/index.ts
+++ b/crypto/_fnv/mod.ts
@@ -4,7 +4,7 @@
 import { fnv32, fnv32a } from "./fnv32.ts";
 import { fnv64, fnv64a } from "./fnv64.ts";
 
-export const fnv = (name: string, buf: Uint8Array | undefined): ArrayBuffer => {
+export function fnv(name: string, buf?: Uint8Array): ArrayBuffer {
   if (!buf) {
     throw new TypeError("no data provided for hashing");
   }
@@ -21,4 +21,4 @@ export const fnv = (name: string, buf: Uint8Array | undefined): ArrayBuffer => {
     default:
       throw new TypeError(`unsupported fnv digest: ${name}`);
   }
-};
+}
diff --git a/crypto/crypto.ts b/crypto/crypto.ts
index d3a71b7971ec..0c7592a65158 100644
--- a/crypto/crypto.ts
+++ b/crypto/crypto.ts
@@ -175,7 +175,7 @@ import {
   instantiateWasm,
 } from "./_wasm/mod.ts";
 import { timingSafeEqual } from "./timing_safe_equal.ts";
-import { fnv } from "./_fnv/index.ts";
+import { fnv } from "./_fnv/mod.ts";
 
 /**
  * A copy of the global WebCrypto interface, with methods bound so they're