diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c386749..fdc85fd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,7 +40,7 @@ jobs:
       - name: Setup Deno
         uses: denoland/setup-deno@v2
         with:
-          deno-version: 2.5.6
+          deno-version: 2.6.4
           cache: true
 
       - name: Run lint checks
@@ -56,7 +56,7 @@ jobs:
       - name: Setup Deno
         uses: denoland/setup-deno@v2
         with:
-          deno-version: 2.5.6
+          deno-version: 2.6.4
           cache: true
 
       - name: Check code format
@@ -72,7 +72,7 @@ jobs:
       - name: Setup Deno
         uses: denoland/setup-deno@v2
         with:
-          deno-version: 2.5.6
+          deno-version: 2.6.4
           cache: true
 
       - name: Run type checks
@@ -90,7 +90,7 @@ jobs:
       - name: Setup Deno
         uses: denoland/setup-deno@v2
         with:
-          deno-version: 2.5.6
+          deno-version: 2.6.4
           cache: true
 
       - name: Run tests
diff --git a/.github/workflows/compatibility.yml b/.github/workflows/compatibility.yml
index 29a19d9..a80b90a 100644
--- a/.github/workflows/compatibility.yml
+++ b/.github/workflows/compatibility.yml
@@ -40,7 +40,7 @@ jobs:
       - name: Setup Deno
         uses: denoland/setup-deno@v2
         with:
-          deno-version: 2.5.6
+          deno-version: 2.6.4
           cache: true
 
       - name: Run tests
diff --git a/packages/client/spec/request.client.test.ts b/packages/client/spec/request.client.test.ts
index 191cf8c..b439318 100644
--- a/packages/client/spec/request.client.test.ts
+++ b/packages/client/spec/request.client.test.ts
@@ -132,7 +132,10 @@ describe('RequestClient', () => {
     const originalFetch = globalThis.fetch;
     const api = createClient({ timeout: 20 });
     try {
-      globalThis.fetch = (_input, init) =>
+      globalThis.fetch = (
+        _input: RequestInfo | URL,
+        init?: RequestInit & { signal?: AbortSignal | null },
+      ) =>
         new Promise((_resolve, reject) => {
           init?.signal?.addEventListener('abort', () => {
             reject(new DOMException('Timeout', 'TimeoutError'));