diff --git a/openeo_driver/delayed_vector.py b/openeo_driver/delayed_vector.py
index f4a4abe5..4524768f 100644
--- a/openeo_driver/delayed_vector.py
+++ b/openeo_driver/delayed_vector.py
@@ -321,6 +321,6 @@ def _read_geojson_crs(geojson: Dict) -> pyproj.CRS:
         crs = geojson.get("crs", {}).get("properties", {}).get("name")
         return pyproj.CRS("epsg:4326") if crs is None else pyproj.CRS(crs)
 
-    def to_driver_vector_cube(self):
+    def to_driver_vector_cube(self) -> DriverVectorCube:
         gdf = self.as_geodataframe()
         return DriverVectorCube.from_geodataframe(gdf, dimension_name="bands")
diff --git a/openeo_driver/save_result.py b/openeo_driver/save_result.py
index cfab273b..e92b56a6 100644
--- a/openeo_driver/save_result.py
+++ b/openeo_driver/save_result.py
@@ -26,6 +26,8 @@
 import xarray
 
 from openeo.metadata import CollectionMetadata
+from typeguard import typechecked
+
 from openeo_driver.datacube import DriverDataCube, DriverVectorCube, DriverMlModel
 from openeo_driver.datastructs import StacAsset
 from openeo_driver.delayed_vector import DelayedVector
@@ -299,12 +301,12 @@ class AggregatePolygonResult(JSONResult):  # TODO: if it supports NetCDF and CSV
     """
 
     # TODO #71 #114 EP-3981 port this to proper vector cube support
-
+    @typechecked
     def __init__(
         self,
-        timeseries: Dict[int, List[List[Any]]],
+        timeseries: Optional[Dict[str, List[List[Any]]]],
         regions: Union[GeometryCollection, DriverVectorCube],
-        metadata: CollectionMetadata = None,
+        metadata: Optional[CollectionMetadata] = None,
     ):
         """
         :param timeseries: {timestamp: [geometries, bands]}
@@ -1010,7 +1012,7 @@ def to_save_result(data: Any, format: Optional[str] = None, options: Optional[di
             return JSONResult(data.geojson, format="geojson", options=options)
         else:
             data = data.to_driver_vector_cube()
-    elif isinstance(data, DriverDataCube):
+    if isinstance(data, DriverDataCube):
         return ImageCollectionResult(data, format=format, options=options)
     elif isinstance(data, DriverVectorCube):
         return VectorCubeResult(cube=data, format=format, options=options)
diff --git a/setup.py b/setup.py
index a6ef418f..b4f4897d 100644
--- a/setup.py
+++ b/setup.py
@@ -30,6 +30,7 @@
     "pyarrow>=10.0.0",
     "jsonschema",
     "dirty-equals>=0.6",
+    "typeguard",
 ]
 
 typing_require = [
diff --git a/tests/test_save_result_parquet.py b/tests/test_save_result_parquet.py
index ae1a1d48..a2ff1da9 100644
--- a/tests/test_save_result_parquet.py
+++ b/tests/test_save_result_parquet.py
@@ -1,7 +1,8 @@
 import pytest
 
 from openeo_driver.datacube import DriverVectorCube
-from openeo_driver.save_result import AggregatePolygonSpatialResult
+from openeo_driver.delayed_vector import DelayedVector
+from openeo_driver.save_result import AggregatePolygonSpatialResult, to_save_result, VectorCubeResult
 from .data import get_path
 
 import geopandas as gpd
@@ -48,3 +49,12 @@ def test_write_driver_vector_cube_to_parquet(tmp_path):
     vector_cube.write_assets(tmp_path / "dummy", format="Parquet")
 
     assert gpd.read_parquet(tmp_path / "vectorcube.parquet").shape == (2, 3)
+
+
+def test_write_delayed_vector_cube_to_parquet(tmp_path):
+    dv = DelayedVector(str(get_path("geojson/FeatureCollection02.json")))
+    vector_cube = to_save_result(dv, format="parquet")
+    assert isinstance(vector_cube, VectorCubeResult)
+    vector_cube.write_assets(tmp_path / "dummy")
+    # TODO: Why are id and pop columns missing here?
+    assert gpd.read_parquet(tmp_path / "vectorcube.parquet").shape == (2, 1)