diff --git a/lib/modules/platform/github/index.spec.ts b/lib/modules/platform/github/index.spec.ts
index e16f3db73b860ff31a468f970de6ae9bf25b9796..eb133f6ecae99b5898feaab3e854fff8b44e8af2 100644
--- a/lib/modules/platform/github/index.spec.ts
+++ b/lib/modules/platform/github/index.spec.ts
@@ -2568,7 +2568,7 @@ describe('modules/platform/github/index', () => {
       const scope = httpMock.scope(githubApiHost);
       initRepoMock(scope, 'some/repo');
       scope
-        .get('/repos/some/repo/pulls?head=some/repo:branch&state=open')
+        .get('/repos/some/repo/pulls?head=some:branch&state=open')
         .reply(200, [
           {
             number: 1,
@@ -2598,7 +2598,7 @@ describe('modules/platform/github/index', () => {
       const scope = httpMock.scope(githubApiHost);
       initRepoMock(scope, 'some/repo');
       scope
-        .get('/repos/some/repo/pulls?head=some/repo:branch&state=open')
+        .get('/repos/some/repo/pulls?head=some:branch&state=open')
         .reply(200, []);
       await github.initRepo({ repository: 'some/repo' });
       const pr = await github.findPr({
diff --git a/lib/modules/platform/github/index.ts b/lib/modules/platform/github/index.ts
index 1298d0f908f04cd6672a9a72934330f77299ba78..93488565ba630a9d2a97111fd688b7214ed9faa1 100644
--- a/lib/modules/platform/github/index.ts
+++ b/lib/modules/platform/github/index.ts
@@ -855,9 +855,10 @@ export async function findPr({
 
   if (includeOtherAuthors) {
     const repo = config.parentRepo ?? config.repository;
+    const org = repo?.split('/')[0];
     // PR might have been created by anyone, so don't use the cached Renovate PR list
     const { body: prList } = await githubApi.getJson<GhRestPr[]>(
-      `repos/${repo}/pulls?head=${repo}:${branchName}&state=open`,
+      `repos/${repo}/pulls?head=${org}:${branchName}&state=open`,
       { cacheProvider: repoCacheProvider },
     );