diff --git a/package-lock.json b/package-lock.json
index dc2216b..45758f4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -19,7 +19,7 @@
         "@types/node": "^22.0.0",
         "@vitest/coverage-v8": "^3.0.0",
         "esbuild": "^0.25.0",
-        "fetch-mock": "^11.0.0",
+        "fetch-mock": "^12.0.0",
         "glob": "^11.0.0",
         "prettier": "3.4.2",
         "semantic-release-plugin-update-version-in-files": "^1.1.0",
@@ -1398,25 +1398,20 @@
       "license": "MIT"
     },
     "node_modules/fetch-mock": {
-      "version": "11.1.5",
-      "resolved": "https://registry.npmjs.org/fetch-mock/-/fetch-mock-11.1.5.tgz",
-      "integrity": "sha512-KHmZDnZ1ry0pCTrX4YG5DtThHi0MH+GNI9caESnzX/nMJBrvppUHMvLx47M0WY9oAtKOMiPfZDRpxhlHg89BOA==",
+      "version": "12.3.0",
+      "resolved": "https://registry.npmjs.org/fetch-mock/-/fetch-mock-12.3.0.tgz",
+      "integrity": "sha512-+ZHzLuzrKpP3u5PZo8ghFP1Kr3UJUTZ5PT/uQZtLv7UagDCVRt1bSzVg6MoTFdjQ0GXsx/crq2t0tGabkbH2yA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
         "@types/glob-to-regexp": "^0.4.4",
         "dequal": "^2.0.3",
         "glob-to-regexp": "^0.4.1",
-        "is-subset": "^0.1.1",
+        "is-subset-of": "^3.1.10",
         "regexparam": "^3.0.0"
       },
       "engines": {
-        "node": ">=8.0.0"
-      },
-      "peerDependenciesMeta": {
-        "node-fetch": {
-          "optional": true
-        }
+        "node": ">=18.11.0"
       }
     },
     "node_modules/foreground-child": {
@@ -1535,12 +1530,16 @@
         "node": ">=8"
       }
     },
-    "node_modules/is-subset": {
-      "version": "0.1.1",
-      "resolved": "https://registry.npmjs.org/is-subset/-/is-subset-0.1.1.tgz",
-      "integrity": "sha512-6Ybun0IkarhmEqxXCNw/C0bna6Zb/TkfUX9UbwJtK6ObwAVCxmAP308WWTHviM/zAqXk05cdhYsUsZeGQh99iw==",
+    "node_modules/is-subset-of": {
+      "version": "3.1.10",
+      "resolved": "https://registry.npmjs.org/is-subset-of/-/is-subset-of-3.1.10.tgz",
+      "integrity": "sha512-avvaYgVmYWyaZ1NDFiv4y9JGkrE2je3op1Po4VYKKJKR8H2qVPsg1GZuuXl5elCTxTlwAIsrAjWAs4BVrISFRw==",
+      "deprecated": "Package no longer supported. Contact Support at https://www.npmjs.com/support for more info.",
       "dev": true,
-      "license": "MIT"
+      "license": "MIT",
+      "dependencies": {
+        "typedescriptor": "3.0.2"
+      }
     },
     "node_modules/isexe": {
       "version": "2.0.0",
@@ -2288,6 +2287,14 @@
         "node": ">=14.0.0"
       }
     },
+    "node_modules/typedescriptor": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/typedescriptor/-/typedescriptor-3.0.2.tgz",
+      "integrity": "sha512-hyVbaCUd18UiXk656g/imaBLMogpdijIEpnhWYrSda9rhvO4gOU16n2nh7xG5lv/rjumnZzGOdz0CEGTmFe0fQ==",
+      "deprecated": "Package no longer supported. Contact Support at https://www.npmjs.com/support for more info.",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/typescript": {
       "version": "5.7.3",
       "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.7.3.tgz",
diff --git a/package.json b/package.json
index 1cd103a..6427bc3 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
     "@types/node": "^22.0.0",
     "@vitest/coverage-v8": "^3.0.0",
     "esbuild": "^0.25.0",
-    "fetch-mock": "^11.0.0",
+    "fetch-mock": "^12.0.0",
     "glob": "^11.0.0",
     "prettier": "3.4.2",
     "semantic-release-plugin-update-version-in-files": "^1.1.0",
diff --git a/test/check-token.test.ts b/test/check-token.test.ts
index 930a3ea..61a85e1 100644
--- a/test/check-token.test.ts
+++ b/test/check-token.test.ts
@@ -5,7 +5,7 @@ import { checkToken } from "../src/index.js";
 
 describe("checkToken()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://api.github.com/applications/1234567890abcdef1234/token",
       {
         scopes: ["repo"],
@@ -34,7 +34,7 @@ describe("checkToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -60,7 +60,7 @@ describe("checkToken()", () => {
   });
 
   it("GitHub Example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://api.github.com/applications/lv1.1234567890abcdef/token",
       {
         expires_at: "2021-10-06T17:26:27Z",
@@ -90,7 +90,7 @@ describe("checkToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/create-device-code.test.ts b/test/create-device-code.test.ts
index f6a69d6..a751cef 100644
--- a/test/create-device-code.test.ts
+++ b/test/create-device-code.test.ts
@@ -5,7 +5,7 @@ import { createDeviceCode } from "../src/index.js";
 
 describe("createDeviceCode()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/device/code",
       {
         device_code: "devicecode123",
@@ -36,7 +36,7 @@ describe("createDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -53,7 +53,7 @@ describe("createDeviceCode()", () => {
   });
 
   it("GitHub App example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/device/code",
       {
         device_code: "devicecode123",
@@ -82,7 +82,7 @@ describe("createDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/delete-authorization.test.ts b/test/delete-authorization.test.ts
index 253fb9d..a07b8f4 100644
--- a/test/delete-authorization.test.ts
+++ b/test/delete-authorization.test.ts
@@ -5,7 +5,7 @@ import { deleteAuthorization } from "../src/index.js";
 
 describe("deleteAuthorization()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().deleteOnce(
+    const mock = fetchMock.createInstance().deleteOnce(
       "https://api.github.com/applications/1234567890abcdef1234/grant",
       {
         status: 204,
@@ -34,7 +34,7 @@ describe("deleteAuthorization()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -50,7 +50,7 @@ describe("deleteAuthorization()", () => {
   });
 
   it("GitHub App", async () => {
-    const mock = fetchMock.sandbox().deleteOnce(
+    const mock = fetchMock.createInstance().deleteOnce(
       "https://api.github.com/applications/lv1.1234567890abcdef/grant",
       {
         scopes: [],
@@ -80,7 +80,7 @@ describe("deleteAuthorization()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/delete-token.test.ts b/test/delete-token.test.ts
index efbab53..f36cd42 100644
--- a/test/delete-token.test.ts
+++ b/test/delete-token.test.ts
@@ -5,7 +5,7 @@ import { deleteToken } from "../src/index.js";
 
 describe("deleteToken()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().deleteOnce(
+    const mock = fetchMock.createInstance().deleteOnce(
       "https://api.github.com/applications/1234567890abcdef1234/token",
       {
         status: 204,
@@ -34,7 +34,7 @@ describe("deleteToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -50,7 +50,7 @@ describe("deleteToken()", () => {
   });
 
   it("GitHub App", async () => {
-    const mock = fetchMock.sandbox().deleteOnce(
+    const mock = fetchMock.createInstance().deleteOnce(
       "https://api.github.com/applications/lv1.1234567890abcdef/token",
       {
         scopes: [],
@@ -80,7 +80,7 @@ describe("deleteToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/exchange-device-code.test.ts b/test/exchange-device-code.test.ts
index 667360c..ff993a3 100644
--- a/test/exchange-device-code.test.ts
+++ b/test/exchange-device-code.test.ts
@@ -5,7 +5,7 @@ import { exchangeDeviceCode } from "../src/index.js";
 
 describe("exchangeDeviceCode()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -35,7 +35,7 @@ describe("exchangeDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -58,7 +58,7 @@ describe("exchangeDeviceCode()", () => {
   });
 
   it("with scopes", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -89,7 +89,7 @@ describe("exchangeDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -115,7 +115,7 @@ describe("exchangeDeviceCode()", () => {
   });
 
   it("authorization_pending error", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         error: "authorization_pending",
@@ -147,7 +147,7 @@ describe("exchangeDeviceCode()", () => {
               "user-agent": "test",
             },
             request: {
-              fetch: mock,
+              fetch: mock.fetchHandler,
             },
           }),
         }),
@@ -157,7 +157,7 @@ describe("exchangeDeviceCode()", () => {
   });
 
   it("OAuth App with ClientSecret", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -188,7 +188,7 @@ describe("exchangeDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -212,7 +212,7 @@ describe("exchangeDeviceCode()", () => {
   });
 
   it("GitHub App", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -242,7 +242,7 @@ describe("exchangeDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -264,7 +264,7 @@ describe("exchangeDeviceCode()", () => {
   });
 
   it("GitHub App with clientSecret", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -295,7 +295,7 @@ describe("exchangeDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -318,7 +318,7 @@ describe("exchangeDeviceCode()", () => {
   });
 
   it("Refresh token", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         body: {
@@ -356,7 +356,7 @@ describe("exchangeDeviceCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/exchange-web-flow-code.test.ts b/test/exchange-web-flow-code.test.ts
index 4622b97..8460e83 100644
--- a/test/exchange-web-flow-code.test.ts
+++ b/test/exchange-web-flow-code.test.ts
@@ -5,7 +5,7 @@ import { exchangeWebFlowCode } from "../src/index.js";
 
 describe("exchangeWebFlowCode()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -36,7 +36,7 @@ describe("exchangeWebFlowCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -60,7 +60,7 @@ describe("exchangeWebFlowCode()", () => {
   });
 
   it("with scopes", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -91,7 +91,7 @@ describe("exchangeWebFlowCode()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -118,7 +118,7 @@ describe("exchangeWebFlowCode()", () => {
   });
 
   it("All options for OAuth Apps", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://ghe.acme-inc.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -152,7 +152,7 @@ describe("exchangeWebFlowCode()", () => {
         },
         baseUrl: "https://ghe.acme-inc.com/api/v3",
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -176,7 +176,7 @@ describe("exchangeWebFlowCode()", () => {
   });
 
   it("All options for GitHub Apps", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://ghe.acme-inc.com/login/oauth/access_token",
       {
         access_token: "secret123",
@@ -210,7 +210,7 @@ describe("exchangeWebFlowCode()", () => {
         },
         baseUrl: "https://ghe.acme-inc.com/api/v3",
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -233,7 +233,7 @@ describe("exchangeWebFlowCode()", () => {
   });
 
   it("Refresh token", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://ghe.acme-inc.com/login/oauth/access_token",
       {
         body: {
@@ -273,7 +273,7 @@ describe("exchangeWebFlowCode()", () => {
         },
         baseUrl: "https://ghe.acme-inc.com/api/v3",
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/refresh-token.test.ts b/test/refresh-token.test.ts
index ad5bc77..1a80ca3 100644
--- a/test/refresh-token.test.ts
+++ b/test/refresh-token.test.ts
@@ -5,7 +5,7 @@ import { refreshToken } from "../src/index.js";
 
 describe("refreshToken()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://github.com/login/oauth/access_token",
       {
         body: {
@@ -45,7 +45,7 @@ describe("refreshToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/reset-token.test.ts b/test/reset-token.test.ts
index 583740f..e83a2a0 100644
--- a/test/reset-token.test.ts
+++ b/test/reset-token.test.ts
@@ -5,7 +5,7 @@ import { resetToken } from "../src/index.js";
 
 describe("resetToken()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().patchOnce(
+    const mock = fetchMock.createInstance().patchOnce(
       "https://api.github.com/applications/1234567890abcdef1234/token",
       {
         scopes: ["repo"],
@@ -35,7 +35,7 @@ describe("resetToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -62,7 +62,7 @@ describe("resetToken()", () => {
   });
 
   it("GitHub Example", async () => {
-    const mock = fetchMock.sandbox().patchOnce(
+    const mock = fetchMock.createInstance().patchOnce(
       "https://api.github.com/applications/lv1.1234567890abcdef/token",
       {
         expires_at: "2021-10-06T17:26:27Z",
@@ -93,7 +93,7 @@ describe("resetToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
diff --git a/test/scope-token.test.ts b/test/scope-token.test.ts
index 643b85d..db15a3e 100644
--- a/test/scope-token.test.ts
+++ b/test/scope-token.test.ts
@@ -5,7 +5,7 @@ import { scopeToken } from "../src/index.js";
 
 describe("scopeToken()", () => {
   it("README example", async () => {
-    const mock = fetchMock.sandbox().postOnce(
+    const mock = fetchMock.createInstance().postOnce(
       "https://api.github.com/applications/lv1.1234567890abcdef/token/scoped",
       {
         account: {
@@ -46,7 +46,7 @@ describe("scopeToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });
@@ -72,7 +72,7 @@ describe("scopeToken()", () => {
 
   it("passes `expires_at` through", async () => {
     const mock = fetchMock
-      .sandbox()
+      .createInstance()
       .postOnce(
         "https://api.github.com/applications/lv1.1234567890abcdef/token/scoped",
         {
@@ -100,7 +100,7 @@ describe("scopeToken()", () => {
           "user-agent": "test",
         },
         request: {
-          fetch: mock,
+          fetch: mock.fetchHandler,
         },
       }),
     });