diff --git a/tests/unit/image-generation-route.test.ts b/tests/unit/image-generation-route.test.ts
index 11e3dbb53b..1cae8a7eae 100644
--- a/tests/unit/image-generation-route.test.ts
+++ b/tests/unit/image-generation-route.test.ts
@@ -19,6 +19,7 @@ const providerChatRoute =
   await import("../../src/app/api/v1/providers/[provider]/chat/completions/route.ts");
 const imageEditRoute = await import("../../src/app/api/v1/images/edits/route.ts");
 const v1ModelsCatalog = await import("../../src/app/api/v1/models/catalog.ts");
+const { setPinnedFetchTestOverride } = await import("../../src/shared/network/remoteImageFetch.ts");
 
 const originalFetch = globalThis.fetch;
 
@@ -72,6 +73,7 @@ function createCodexEditForm(
 
 async function resetStorage() {
   globalThis.fetch = originalFetch;
+  setPinnedFetchTestOverride(undefined);
   apiKeysDb.resetApiKeyState();
   core.resetDbInstance();
   fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true, maxRetries: 5, retryDelay: 100 });
@@ -120,6 +122,7 @@ test.beforeEach(async () => {
 
 test.after(() => {
   globalThis.fetch = originalFetch;
+  setPinnedFetchTestOverride(undefined);
   apiKeysDb.resetApiKeyState();
   core.resetDbInstance();
   fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true, maxRetries: 5, retryDelay: 100 });
@@ -234,7 +237,7 @@ test("v1 image models GET exposes current Codex image models and hides inactive
 test("v1 image generation POST accepts promptless requests for image-only models", async () => {
   await seedConnection("topaz", { apiKey: "topaz-key" });
 
-  globalThis.fetch = async (url, options: RequestInit = {}) => {
+  const mockFetchImpl = async (url, options: RequestInit = {}) => {
     const stringUrl = String(url);
     if (stringUrl === "https://example.com/topaz-input.png") {
       return new Response(new Uint8Array([1, 2, 3]), {
@@ -254,6 +257,11 @@ test("v1 image generation POST accepts promptless requests for image-only models
 
     throw new Error(`Unexpected URL: ${stringUrl}`);
   };
+  // #13883: resolveImageSource now sets `pinDns: true`, which pins the connection via a
+  // real undici socket and would bypass this mocked globalThis.fetch — route it through
+  // the test-only pinned-fetch override instead (src/shared/network/remoteImageFetch.ts).
+  globalThis.fetch = mockFetchImpl;
+  setPinnedFetchTestOverride(mockFetchImpl);
 
   const response = await imageRoute.POST(
     new Request("http://localhost/api/v1/images/generations", {