diff --git a/src/caoscrawler/scanner.py b/src/caoscrawler/scanner.py
index dda27c8a797915be2a30769fa4c5f45637ae44d9..9e79d813cd5f407c61ea49f94970c7cc513d12f9 100644
--- a/src/caoscrawler/scanner.py
+++ b/src/caoscrawler/scanner.py
@@ -301,14 +301,14 @@ def scanner(items: list[StructureElement],
                 children = converter.create_children(general_store_copy, element)
 
                 # add provenance information for each variable
-                self.debug_tree.debug_tree[str(element)] = (
+                debug_tree.debug_tree[str(element)] = (
                     general_store_copy.get_storage(), record_store_copy.get_storage())
-                self.debug_tree.debug_metadata["copied"][str(element)] = (
+                debug_tree.debug_metadata["copied"][str(element)] = (
                     general_store_copy.get_dict_copied(),
                     record_store_copy.get_dict_copied())
-                self.debug_tree.debug_metadata["usage"][str(element)].add(
+                debug_tree.debug_metadata["usage"][str(element)].add(
                     "/".join(converters_path + [converter.name]))
-                mod_info = self.debug_tree.debug_metadata["provenance"]
+                mod_info = debug_tree.debug_metadata["provenance"]
                 for record_name, prop_name in keys_modified:
                     # TODO: check
                     internal_id = record_store_copy.get_internal_id(