diff --git a/src/mintpy/objects/gnss.py b/src/mintpy/objects/gnss.py
index 51b6cc4c3..b4de31d27 100644
--- a/src/mintpy/objects/gnss.py
+++ b/src/mintpy/objects/gnss.py
@@ -1082,6 +1082,8 @@ def get_site_lat_lon(self, print_msg=False) -> (float, float):
         """
         # need to refer to the site list
         site_list_file = os.path.basename(GNSS_SITE_LIST_URLS['SIDESHOW'])
+        if not os.path.exists(site_list_file):
+            dload_site_list(out_file=site_list_file, source=self.source, print_msg=True)
 
         # find site in site list file
         with open(site_list_file) as site_list: