diff --git a/pageindex/utils.py b/pageindex/utils.py
index f00ccf3a7..235dd09cc 100644
--- a/pageindex/utils.py
+++ b/pageindex/utils.py
@@ -16,6 +16,7 @@
 import yaml
 from pathlib import Path
 from types import SimpleNamespace as config
+import re
 
 # Backward compatibility: support CHATGPT_API_KEY as alias for OPENAI_API_KEY
 if not os.getenv("OPENAI_API_KEY") and os.getenv("CHATGPT_API_KEY"):