diff --git a/web/js/algorithms/fast.ts b/web/js/algorithms/fast.ts
index 82a9a778..32f0eaa1 100644
--- a/web/js/algorithms/fast.ts
+++ b/web/js/algorithms/fast.ts
@@ -1,3 +1,5 @@
+import { ChallengeResult } from "./types";
+
 type ProgressCallback = (nonce: number) => void;
 
 interface ProcessOptions {
@@ -17,7 +19,7 @@ export default function process(
   signal: AbortSignal | null = null,
   progressCallback?: ProgressCallback,
   threads: number = Math.trunc(Math.max(getHardwareConcurrency() / 2, 1)),
-): Promise<string> {
+): Promise<ChallengeResult> {
   console.debug("fast algo");
 
   // Choose worker based on secure context.
diff --git a/web/js/algorithms/index.ts b/web/js/algorithms/index.ts
index 2781aef0..d67b4829 100644
--- a/web/js/algorithms/index.ts
+++ b/web/js/algorithms/index.ts
@@ -1,5 +1,7 @@
 import fast from "./fast";
 
+export type { ChallengeResult } from "./types";
+
 export default {
   fast: fast,
   slow: fast, // XXX(Xe): slow is deprecated, but keep this around in case anything goes bad
diff --git a/web/js/algorithms/types.ts b/web/js/algorithms/types.ts
new file mode 100644
index 00000000..03cc7157
--- /dev/null
+++ b/web/js/algorithms/types.ts
@@ -0,0 +1,6 @@
+export interface ChallengeResult {
+  hash: string;
+  data: string;
+  difficulty: number;
+  nonce: number;
+}
\ No newline at end of file
diff --git a/web/js/main.tsx b/web/js/main.tsx
index 32e39ad3..40ae427e 100644
--- a/web/js/main.tsx
+++ b/web/js/main.tsx
@@ -1,6 +1,6 @@
 import { render } from "preact";
 import { useState, useEffect, useRef } from "preact/hooks";
-import algorithms from "./algorithms";
+import algorithms, { ChallengeResult } from "./algorithms";
 
 // from Xeact
 const u = (url: string = "", params: Record<string, any> = {}) => {
@@ -211,7 +211,7 @@ function App({ anubisVersion, basePrefix }: AppProps) {
         }
       },
     )
-      .then((result: any) => {
+      .then((result: ChallengeResult) => {
         const t1 = Date.now();
         const { hash, nonce } = result;