diff --git a/src/env_file_helper.py b/src/env_file_helper.py
index 29fb914..80f4d31 100644
--- a/src/env_file_helper.py
+++ b/src/env_file_helper.py
@@ -28,7 +28,7 @@ def _is_rule_satisfied(in_list: list, rule: DependencyRule) -> tuple[bool, int]:
     return parent_index < child_index, parent_index
 
 
-def sort_env_files_by_rule(env_list: list[EnvFile], rules: list[DependencyRule]) -> list:
+def sort_env_files_by_rule(env_list: list[EnvFile], rules: list[DependencyRule]) -> list[EnvFile]:
     in_list = env_list.copy()
 
     def swap_item_with_previous(in_list: list[EnvFile], index: int):