diff --git a/src/power_grid_model_io/utils/download.py b/src/power_grid_model_io/utils/download.py
index 631a9ffc..88731aeb 100644
--- a/src/power_grid_model_io/utils/download.py
+++ b/src/power_grid_model_io/utils/download.py
@@ -215,7 +215,7 @@ def get_download_path(
     """
 
     # If no specific download path was given, we need to generate a unique key (based on the given unique key)
-    if dir_path is None or file_name is None:
+    if file_name is None or unique_key is not None:
         if unique_key is None:
             raise ValueError("Supply a unique key in order to auto generate a download path.")
 
@@ -228,8 +228,7 @@ def get_download_path(
         if file_name is None:
             file_name = Path(f"{unique_key}.download")
         # Otherwise, use the unique key as a sub directory
-        else:
-            assert dir_path is None  # sanity check
+        elif dir_path is None:
             dir_path = Path(tempfile.gettempdir()) / unique_key
 
     # If no dir_path is given, use the system's designated folder for temporary files.
diff --git a/tests/unit/utils/test_download.py b/tests/unit/utils/test_download.py
index 98d74eb3..8db11c3d 100644
--- a/tests/unit/utils/test_download.py
+++ b/tests/unit/utils/test_download.py
@@ -26,6 +26,8 @@
 # The / and + will be replaced with a _ and - character and the trailing = character(s) will be removed.
 FOO_KEY = "LCa0a2j_xo_5m0U8HTBBNBNCLXBkg7-g-YpeiGJm564"
 
+TEMP_DIR = Path(tempfile.gettempdir()).resolve()
+
 
 @pytest.fixture()
 def temp_dir():
@@ -374,12 +376,20 @@ def test_get_download_path__ignore_unique_key(temp_dir: Path):
     assert path == temp_dir / "file_name.zip"
 
 
+def test_get_download_path__temp_dir():
+    # Act
+    path = get_download_path(file_name="file_name.zip")
+
+    # Assert
+    assert path == TEMP_DIR / "file_name.zip"
+
+
 def test_get_download_path__auto_dir():
     # Act
     path = get_download_path(file_name="file_name.zip", unique_key="foo")
 
     # Assert
-    assert path == Path(tempfile.gettempdir()).resolve() / FOO_KEY / "file_name.zip"
+    assert path == TEMP_DIR / FOO_KEY / "file_name.zip"
 
 
 def test_get_download_path__auto_file_name(temp_dir: Path):