diff --git a/iyp/__init__.py b/iyp/__init__.py
index 7e393c5..5e0e28e 100644
--- a/iyp/__init__.py
+++ b/iyp/__init__.py
@@ -50,7 +50,7 @@ def batch_format_link_properties(links: list, inplace=True) -> list:
         for link in links:
             for idx, prop_dict in enumerate(link['props']):
                 link['props'][idx] = format_properties(prop_dict)
-        return links
+        return None
     return [{'src_id': link['src_id'],
              'dst_id': link['dst_id'],
              'props': [format_properties(d) for d in link['props']]}