diff --git a/src/infra/provider-usage.auth.normalizes-keys.test.ts b/src/infra/provider-usage.auth.normalizes-keys.test.ts
index 0309a63c7f6..03938076964 100644
--- a/src/infra/provider-usage.auth.normalizes-keys.test.ts
+++ b/src/infra/provider-usage.auth.normalizes-keys.test.ts
@@ -4,10 +4,15 @@ import path from "node:path";
 import { afterAll, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import { NON_ENV_SECRETREF_MARKER } from "../agents/model-auth-markers.js";
 
-const resolveProviderUsageAuthWithPluginMock = vi.fn(async () => null);
+type ResolveProviderUsageAuthWithPlugin =
+  typeof import("../plugins/provider-runtime.js").resolveProviderUsageAuthWithPlugin;
+
+const resolveProviderUsageAuthWithPluginMock = vi.fn<ResolveProviderUsageAuthWithPlugin>(
+  async () => null,
+);
 
 vi.mock("../plugins/provider-runtime.js", () => ({
-  resolveProviderUsageAuthWithPlugin: (...args: unknown[]) =>
+  resolveProviderUsageAuthWithPlugin: (...args: Parameters<ResolveProviderUsageAuthWithPlugin>) =>
     resolveProviderUsageAuthWithPluginMock(...args),
 }));