diff --git a/src/core/PullRequest.ts b/src/core/PullRequest.ts
index cf4c518..a5f9aed 100644
--- a/src/core/PullRequest.ts
+++ b/src/core/PullRequest.ts
@@ -7,7 +7,6 @@ import AnonymousError from "./AnonymousError";
 import { IAnonymizedPullRequestDocument } from "./model/anonymizedPullRequests/anonymizedPullRequests.types";
 import AnonymizedPullRequestModel from "./model/anonymizedPullRequests/anonymizedPullRequests.model";
 import config from "../config";
-import got, { HTTPError } from "got";
 import { octokit } from "./GitHubUtils";
 import { ContentAnonimizer } from "./anonymize-utils";
 import { createLogger } from "./logger";
@@ -103,24 +102,15 @@ export default class PullRequest {
         throw err;
       });
 
-    const diffPromise = got(
-      `https://github.com/${owner}/${repo}/pull/${pull_number}.diff`
-    ).catch((err) => {
-      if (err instanceof HTTPError && err.response.statusCode === 404) {
-        logger.warn("PR diff 404, continuing without it", {
-          code: "pr_diff_not_found",
-          httpStatus: 404,
-          pr: `${owner}/${repo}#${pull_number}`,
-        });
-        return { body: "" };
-      }
-      throw err;
+    const diffPromise = oct.rest.pulls.get({
+      owner, repo, pull_number,
+      mediaType: { format: "diff" },
     });
 
     const [comments, diff] = await Promise.all([commentsPromise, diffPromise]);
 
     this._model.pullRequest = {
-      diff: diff.body,
+      diff: diff.data as unknown as string,
       title: prInfo.data.title,
       body: prInfo.data.body || "",
       creationDate: new Date(prInfo.data.created_at),
diff --git a/test/production-regressions.test.js b/test/production-regressions.test.js
index ac056c7..1132f76 100644
--- a/test/production-regressions.test.js
+++ b/test/production-regressions.test.js
@@ -175,6 +175,23 @@ describe("production regressions", function () {
     await gist.download();
     expect(gist.toJSON().gist.files[0].content).to.equal("complete gist content");
   });
+
+  it("retrieves private PR diffs with the authenticated API", async function () {
+    const PR = require("../src/core/PullRequest").default;
+    const pr = new PR(new (require("../src/core/model/anonymizedPullRequests/anonymizedPullRequests.model").default)({ source: { repositoryFullName: "owner/repo", pullRequestId: 1 } }));
+    pr.getToken = async () => "private-token";
+    let diffRequested = false;
+    stub(gh, "octokit", token => {
+      expect(token).to.equal("private-token");
+      return { rest: { pulls: { get: async options => {
+        if (options.mediaType?.format === "diff") { diffRequested = true; return { data: "private diff" }; }
+        return { data: { title: "PR", base: { repo: { full_name: "owner/repo" } }, head: {} } };
+      } } }, paginate: async () => [] };
+    });
+    await pr.download();
+    expect(diffRequested).to.equal(true);
+    expect(pr.model.pullRequest.diff).to.equal("private diff");
+  });
   it("checks GitHub authorization before returning shared cached metadata", async function () {
     const CachedRepoModel = require("../src/core/model/repositories/repositories.model").default;
     stub(db, "isConnected", true);