diff --git a/post_merge_cleanup_proof.py b/post_merge_cleanup_proof.py
index e1c156d..6562a04 100644
--- a/post_merge_cleanup_proof.py
+++ b/post_merge_cleanup_proof.py
@@ -209,7 +209,7 @@ def assess_post_merge_cleanup_proof(
 
     if not remote_delete and not worktree_remove:
         cleanup_mutations = re.search(
-            r"cleanup mutations\s*:\s*(?!none\b)(.+)",
+            r"cleanup mutations\s*:\s*(?!none\b)\S",
             text,
             re.IGNORECASE,
         )