diff --git a/opendm/shots.py b/opendm/shots.py
index 5f472a13..c4698118 100644
--- a/opendm/shots.py
+++ b/opendm/shots.py
@@ -100,7 +100,7 @@ def merge_geojson_shots(geojson_shots_files, output_geojson_file):
         with open(shot_file, "r") as f:
             shots = json.loads(f.read())
 
-        if result is None:
+        if len(result) == 0:
             for feat in shots.get('features', []):
                 added_files[feat['properties']['filename']] = True