diff --git a/pydantic/env_settings.py b/pydantic/env_settings.py
index 3246e96..ea4f0a4 100644
--- a/pydantic/env_settings.py
+++ b/pydantic/env_settings.py
@@ -58,3 +58,4 @@ class BaseSettings(BaseModel):
         env_prefix = 'APP_'
         validate_all = True
         ignore_extra = False
+        arbitrary_types_allowed = True