diff --git a/src/lib/__tests__/github/fetchRepositories.test.ts b/src/lib/__tests__/github/fetchRepositories.test.ts
deleted file mode 100644
index 7f47f97..0000000
--- a/src/lib/__tests__/github/fetchRepositories.test.ts
+++ /dev/null
@@ -1,95 +0,0 @@
-import { describe, it, expect } from "vitest";
-import { mockFetch, jsonResponse, MOCK_REPOS_GRAPHQL } from "./setup";
-
-describe("fetchRepositories", () => {
-  it("GraphQL レスポンスから言語統計を正しく集計する", async () => {
-    mockFetch.mockResolvedValueOnce(jsonResponse(MOCK_REPOS_GRAPHQL)); // POST graphql
-
-    const { fetchRepositories } = await import("../../github");
-    const result = await fetchRepositories("testuser", "fake-token");
-
-    // フォークを除外した2リポジトリ
-    expect(result.totalCount).toBe(2);
-
-    // 言語統計: Python 8000bytes, TypeScript 5000bytes, JavaScript 2000bytes
-    expect(result.languages.length).toBeGreaterThanOrEqual(2);
-    expect(result.languages[0].name).toBe("Python");
-    expect(result.languages[0].bytes).toBe(8000);
-    expect(result.languages[1].name).toBe("TypeScript");
-    expect(result.languages[1].bytes).toBe(5000);
-  });
-
-  it("GraphQL レスポンスからトピックを正しく集計する", async () => {
-    mockFetch.mockResolvedValueOnce(jsonResponse(MOCK_REPOS_GRAPHQL));
-
-    const { fetchRepositories } = await import("../../github");
-    const result = await fetchRepositories("testuser", "fake-token");
-
-    const topicNames = result.topics.map((t) => t.name);
-    expect(topicNames).toContain("react");
-    expect(topicNames).toContain("nextjs");
-    expect(topicNames).toContain("machine-learning");
-  });
-
-  it("言語のパーセンテージが正しく計算される", async () => {
-    mockFetch.mockResolvedValueOnce(jsonResponse(MOCK_REPOS_GRAPHQL));
-
-    const { fetchRepositories } = await import("../../github");
-    const result = await fetchRepositories("testuser", "fake-token");
-
-    const totalBytes = result.languages.reduce((sum, l) => sum + l.bytes, 0);
-    expect(totalBytes).toBe(15000); // 5000 + 2000 + 8000
-
-    for (const lang of result.languages) {
-      const expectedPct = Math.round((lang.bytes / totalBytes) * 1000) / 10;
-      expect(lang.percentage).toBe(expectedPct);
-    }
-  });
-
-  it("topRepos は最大5件で stargazerCount 順に返される", async () => {
-    mockFetch.mockResolvedValueOnce(jsonResponse(MOCK_REPOS_GRAPHQL));
-
-    const { fetchRepositories } = await import("../../github");
-    const result = await fetchRepositories("testuser", "fake-token");
-
-    expect(result.topRepos.length).toBeLessThanOrEqual(5);
-    expect(result.topRepos[0].name).toBe("repo-a");
-    expect(result.topRepos[0].stargazerCount).toBe(50);
-  });
-
-  it("token なしの場合 REST にフォールバックする", async () => {
-    const restRepos = [
-      {
-        name: "rest-repo",
-        description: "A REST repo",
-        html_url: "https://github.com/testuser/rest-repo",
-        stargazers_count: 25,
-        forks_count: 3,
-        fork: false,
-        language: "JavaScript",
-        topics: ["web"],
-      },
-    ];
-    mockFetch.mockResolvedValueOnce(jsonResponse(restRepos));
-
-    const { fetchRepositories } = await import("../../github");
-    const result = await fetchRepositories("testuser");
-
-    expect(result.totalCount).toBe(1);
-    expect(result.topRepos[0].name).toBe("rest-repo");
-    expect(result.languages[0].name).toBe("JavaScript");
-  });
-
-  it("ユーザーが存在しない場合 UserNotFoundError をスローする", async () => {
-    mockFetch.mockResolvedValueOnce(
-      jsonResponse({ data: { user: null } })
-    );
-
-    const { fetchRepositories } = await import("../../github");
-    const { UserNotFoundError } = await import("../../types");
-
-    await expect(fetchRepositories("nonexistent", "fake-token")).rejects.toThrow(
-      UserNotFoundError
-    );
-  });
-});
diff --git a/src/lib/github.ts b/src/lib/github.ts
index ed7dd37..df06c2e 100644
--- a/src/lib/github.ts
+++ b/src/lib/github.ts
@@ -301,7 +301,7 @@ type RepositoriesResponse = {
  * @throws {UserNotFoundError} ユーザーが存在しない場合
  * @throws {RateLimitError} APIレート制限に達した場合
  */
-export const fetchRepositories = cache(async function fetchRepositories(
+const fetchRepositories = cache(async function fetchRepositories(
   username: string,
   token?: string
 ): Promise<RepositoryData> {