diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index 9a1bf957c..fd6a1b212 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -165,7 +165,9 @@ jobs:
           fi
 
       - name: Upload coverage reports to Codecov
-        if: inputs.coverage == 'ON'
+        # PRs from external contributors fail: https://github.com/codecov/feedback/issues/301
+        # Only upload coverage reports for PRs from the same repo (not forks)
+        if: inputs.coverage == 'ON' && github.event.pull_request.head.repo.full_name == github.repository
         uses: codecov/codecov-action@v4
         with:
           fail_ci_if_error: true