diff --git a/src/adsb/combine_chunks_to_csv.py b/src/adsb/combine_chunks_to_csv.py
index 47a0e43..113a45e 100644
--- a/src/adsb/combine_chunks_to_csv.py
+++ b/src/adsb/combine_chunks_to_csv.py
@@ -14,6 +14,7 @@ Usage:
     python -m src.adsb.combine_chunks_to_csv --chunks-dir data/output/adsb_chunks --start-date 2024-01-01 --end-date 2024-01-07 --skip-base
 """
 import gc
+import gzip
 import os
 import sys
 import glob