diff --git a/lib/tests/formulae_detect.rb b/lib/tests/formulae_detect.rb
index 2df47f0b..7ac8d0da 100644
--- a/lib/tests/formulae_detect.rb
+++ b/lib/tests/formulae_detect.rb
@@ -44,7 +44,7 @@ def detect_formulae!(args:)
           # Use GitHub Actions variables for pull request jobs.
           if github_ref.present? && github_repository.present? &&
              %r{refs/pull/(?<pr>\d+)/merge} =~ github_ref
-            url = "https://github.com/#{github_repository}/pull/#{pr}/checks"
+            url = "https://github.com/#{github_repository}/pull/#{Regexp.last_match(:pr)}/checks"
           end
         elsif (canonical_formula_name = safe_formula_canonical_name(@argument, args:))
           unless canonical_formula_name.include?("/")