diff --git a/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3/chs3_base/core/us_connection.py b/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3/chs3_base/core/us_connection.py
index df5bf09ea..1919e3e62 100644
--- a/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3/chs3_base/core/us_connection.py
+++ b/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3/chs3_base/core/us_connection.py
@@ -122,9 +122,7 @@ def s3_access_key_id(self) -> str:
     def s3_secret_access_key(self) -> str:
         return self._connector_settings.SECRET_ACCESS_KEY
 
-    def get_full_s3_filename(self, s3_filename_suffix: Optional[str]) -> Optional[str]:
-        if s3_filename_suffix is None:
-            return None
+    def get_full_s3_filename(self, s3_filename_suffix: str) -> str:
         assert self.uuid and self.raw_tenant_id
         return "_".join((self.raw_tenant_id, self.uuid, s3_filename_suffix))
 
diff --git a/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3_tests/db/conftest.py b/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3_tests/db/conftest.py
index ee8cc51d7..ee458f9b0 100644
--- a/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3_tests/db/conftest.py
+++ b/lib/dl_connector_bundle_chs3/dl_connector_bundle_chs3_tests/db/conftest.py
@@ -17,7 +17,7 @@ def pytest_configure(config):  # noqa
 
 @pytest.fixture(autouse=True)
 def patch_get_full_s3_filename(monkeypatch: pytest.MonkeyPatch) -> None:
-    def _patched(self: Any, s3_filename_suffix: Optional[str]) -> Optional[str]:  # type: ignore
+    def _patched(self: Any, s3_filename_suffix: str) -> str:  # type: ignore
         return s3_filename_suffix
 
     monkeypatch.setattr(BaseFileS3Connection, "get_full_s3_filename", _patched)