diff --git a/Library/Homebrew/utils/github.rb b/Library/Homebrew/utils/github.rb
index 33d60a8cb3..c017a63b37 100644
--- a/Library/Homebrew/utils/github.rb
+++ b/Library/Homebrew/utils/github.rb
@@ -441,7 +441,7 @@ module GitHub
     base_url = "#{API_URL}/repos/#{user}/#{repo}"
     pr_payload = open_api("#{base_url}/pulls/#{pr}", scopes: scopes)
     pr_sha = pr_payload["head"]["sha"]
-    pr_branch = pr_payload["head"]["ref"]
+    pr_branch = URI.encode_www_form_component(pr_payload["head"]["ref"])
 
     workflow = open_api("#{base_url}/actions/workflows/#{workflow_id}/runs?branch=#{pr_branch}", scopes: scopes)
     workflow_run = workflow["workflow_runs"].select do |run|