diff --git a/pr_agent/tools/pr_update_changelog.py b/pr_agent/tools/pr_update_changelog.py
index 10547534..fadf28f1 100644
--- a/pr_agent/tools/pr_update_changelog.py
+++ b/pr_agent/tools/pr_update_changelog.py
@@ -113,6 +113,8 @@ class PRUpdateChangelog:
 
         # post-process the response
         response = response.strip()
+        if not response:
+            return ""
         if response.startswith("```"):
             response_lines = response.splitlines()
             response_lines = response_lines[1:]