diff --git a/.all-contributorsrc b/.all-contributorsrc
index 12447ce2..d1aa0a24 100644
--- a/.all-contributorsrc
+++ b/.all-contributorsrc
@@ -1465,6 +1465,16 @@
       "contributions": [
         "review"
       ]
+    },
+    {
+      "login": "IKatsuba",
+      "name": "Igor Katsuba",
+      "avatar_url": "https://avatars.githubusercontent.com/u/10637135?v=4",
+      "profile": "https://blog.katsuba.dev",
+      "contributions": [
+        "ideas",
+        "code"
+      ]
     }
   ]
 }
diff --git a/README.md b/README.md
index 4e1727d4..7947cffc 100644
--- a/README.md
+++ b/README.md
@@ -314,6 +314,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
       <td align="center" valign="top" width="11.11%"><a href="https://nometa.xyz/"><img src="https://avatars.githubusercontent.com/u/68379695?v=4?s=100" width="100px;" alt="Mased"/><br /><sub><b>Mased</b></sub></a><br /><a href="#translation-MasedMSD" title="Translation">🌍</a> <a href="/grammyjs/grammY/commits?author=MasedMSD" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="11.11%"><a href="/ExposedCat"><img src="https://avatars.githubusercontent.com/u/44642024?v=4?s=100" width="100px;" alt="Artem Prokop"/><br /><sub><b>Artem Prokop</b></sub></a><br /><a href="#userTesting-ExposedCat" title="User Testing">📓</a></td>
       <td align="center" valign="top" width="11.11%"><a href="https://chinoman10.com/"><img src="https://avatars.githubusercontent.com/u/8300763?v=4?s=100" width="100px;" alt="Sérgio Rebelo"/><br /><sub><b>Sérgio Rebelo</b></sub></a><br /><a href="/grammyjs/grammY/pulls?q=is%3Apr+reviewed-by%3AChinoman10" title="Reviewed Pull Requests">👀</a></td>
+      <td align="center" valign="top" width="11.11%"><a href="https://blog.katsuba.dev"><img src="https://avatars.githubusercontent.com/u/10637135?v=4?s=100" width="100px;" alt="Igor Katsuba"/><br /><sub><b>Igor Katsuba</b></sub></a><br /><a href="#ideas-IKatsuba" title="Ideas, Planning, & Feedback">🤔</a> <a href="/grammyjs/grammY/commits?author=IKatsuba" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>
diff --git a/package.json b/package.json
index a0117388..b395ef66 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
     "name": "grammy",
     "description": "The Telegram Bot Framework.",
-    "version": "1.31.0",
+    "version": "1.31.1",
     "author": "KnorpelSenf",
     "license": "MIT",
     "engines": {
diff --git a/src/core/client.ts b/src/core/client.ts
index 197f8c30..f707a593 100644
--- a/src/core/client.ts
+++ b/src/core/client.ts
@@ -205,6 +205,12 @@ export interface ApiClientOptions {
         NonNullable<Parameters<typeof fetch>[1]>,
         "method" | "headers" | "body"
     >;
+
+    /**
+     * `fetch` function to use for making HTTP requests. Default: `node-fetch` in Node.js, `fetch` in Deno.
+     */
+    fetch?: typeof fetch;
+
     /**
      * When the network connection is unreliable and some API requests fail
      * because of that, grammY will throw errors that tell you exactly which
@@ -222,6 +228,8 @@ export interface ApiClientOptions {
 class ApiClient<R extends RawApi> {
     private readonly options: Required<ApiClientOptions>;
 
+    private readonly fetch: typeof fetch;
+
     private hasUsedWebhookReply = false;
 
     readonly installedTransformers: Transformer<R>[] = [];
@@ -244,7 +252,9 @@ class ApiClient<R extends RawApi> {
             },
             canUseWebhookReply: options.canUseWebhookReply ?? (() => false),
             sensitiveLogs: options.sensitiveLogs ?? false,
+            fetch: options.fetch ?? fetch,
         };
+        this.fetch = this.options.fetch;
         if (this.options.apiRoot.endsWith("/")) {
             throw new Error(
                 `Remove the trailing '/' from the 'apiRoot' option (use '${
@@ -297,7 +307,7 @@ class ApiClient<R extends RawApi> {
         const sig = controller.signal;
         const options = { ...opts.baseFetchConfig, signal: sig, ...config };
         // Perform fetch call, and handle networking errors
-        const successPromise = fetch(
+        const successPromise = this.fetch(
             url instanceof URL ? url.href : url,
             options,
         ).catch(toHttpError(method, opts.sensitiveLogs));
diff --git a/test/deps.test.ts b/test/deps.test.ts
index c799a186..3460db1f 100644
--- a/test/deps.test.ts
+++ b/test/deps.test.ts
@@ -12,23 +12,7 @@ export {
 export { afterEach, beforeEach, describe, it } from "jsr:@std/testing/bdd";
 export { type Spy, spy, type Stub, stub } from "jsr:@std/testing/mock";
 export { assertType, type IsExact } from "jsr:@std/testing/types";
-
-/**
- * Checks if the actual type `A` is assignable to the expected type `E`, and
- * vice versa.
- *
- * ```ts
- * // false because E is not assignable to A
- * type P = IsMutuallyAssignable<string & RegExpMatchArray, string>;
- * // false because A is not assignable to E
- * type Q = IsMutuallyAssignable<string | RegExpMatchArray, string>;
- * // true
- * type R = IsMutuallyAssignable<string | (string & RegExpMatchArray), string>;
- * ```
- */
-export type IsMutuallyAssignable<A, E> = [E] extends [A]
-    ? [A] extends [E] ? true : false
-    : false;
+export { type IsMutuallyAssignable } from "jsr:@std/testing/unstable-types";
 
 /**
  * Collects a potentially async iterator of `Uint8Array` objects into a single