diff --git a/agent/base_agent.py b/agent/base_agent.py
index e5e64b6ed..a0a64c140 100644
--- a/agent/base_agent.py
+++ b/agent/base_agent.py
@@ -75,6 +75,9 @@ def _filter_code(self, raw_code_block: str) -> str:
         line for line in raw_code_block.splitlines()
         if not line.strip().startswith('```')
     ]
+    # Sometimes LLM returns a build script containing only comments.
+    if all(line.strip().startswith('#') for line in filtered_lines):
+      return ''
     filtered_code_block = '\n'.join(filtered_lines)
     return filtered_code_block