diff --git a/modules/util/gfs_reader.py b/modules/util/gfs_reader.py
index 2143b4da310e9da1c74f6749b97b0a94e1f01eb8..d1f36a4f706ba5c9ca29b173088ace58f01aef00 100644
--- a/modules/util/gfs_reader.py
+++ b/modules/util/gfs_reader.py
@@ -1,6 +1,7 @@
 import datetime
 from datetime import timezone
 import glob
+import os
 import numpy as np
 import xarray as xr
 from util.util import value_to_index