diff --git a/tools/uncompressedsize.py b/tools/uncompressedsize.py
index 32ba0957c..4ed9a772a 100644
--- a/tools/uncompressedsize.py
+++ b/tools/uncompressedsize.py
@@ -34,9 +34,13 @@ def backfill_sizes():
         uuid = image_storage.uuid
         with_locations = model.get_storage_by_uuid(uuid)
 
-        json_string = store.get_content(with_locations.locations, store.image_json_path(uuid))
-        json_data = json.loads(json_string)
-        size = json_data.get('Size', json_data.get('size', -1))
+        try:
+          json_string = store.get_content(with_locations.locations, store.image_json_path(uuid))
+          json_data = json.loads(json_string)
+          size = json_data.get('Size', json_data.get('size', -1))
+        except IOError:
+          logger.debug('Image storage with no json %s', uuid)
+          size = -1
 
         if size == -1:
           missing += 1