diff --git a/openeo_driver/datacube.py b/openeo_driver/datacube.py
index bdec1d90..1351b7be 100644
--- a/openeo_driver/datacube.py
+++ b/openeo_driver/datacube.py
@@ -224,7 +224,9 @@ class DriverVectorCube:
     DIM_PROPERTIES = "properties"
     COLUMN_SELECTION_ALL = "all"
     COLUMN_SELECTION_NUMERICAL = "numerical"
-    VECTOR_CUBE_DUMMY = "vector_cube_dummy"
+
+    # Xarray cube attribute to indicate that it is a dummy cube
+    CUBE_ATTR_VECTOR_CUBE_DUMMY = "vector_cube_dummy"
 
     def __init__(
         self,
@@ -325,7 +327,7 @@ def from_geodataframe(
                 data=numpy.full(shape=[data.shape[0]], fill_value=numpy.nan),
                 dims=[cls.DIM_GEOMETRIES],
                 coords={cls.DIM_GEOMETRIES: data.geometry.index.to_list()},
-                attrs={cls.VECTOR_CUBE_DUMMY: True},
+                attrs={cls.CUBE_ATTR_VECTOR_CUBE_DUMMY: True},
             )
             return cls(geometries=data, cube=cube)
 
@@ -419,7 +421,7 @@ def _as_geopandas_df(
         """Join geometries and cube as a geopandas dataframe"""
         # TODO: avoid copy?
         df = self._geometries.copy(deep=True)
-        if self._cube is not None and not self._cube.attrs.get(self.VECTOR_CUBE_DUMMY):
+        if self._cube is not None and not self._cube.attrs.get(self.CUBE_ATTR_VECTOR_CUBE_DUMMY):
             assert self._cube.dims[0] == self.DIM_GEOMETRIES
             # TODO: better way to combine cube with geometries
             # Flatten multiple (non-geometry) dimensions from cube to new properties in geopandas dataframe
@@ -514,7 +516,7 @@ def to_legacy_save_result(self) -> Union["AggregatePolygonResult", "JSONResult"]
         # TODO: eliminate these legacy, non-standard formats?
         from openeo_driver.save_result import AggregatePolygonResult, JSONResult
 
-        if self._cube is None:
+        if self._cube is None or self._cube.attrs.get(self.CUBE_ATTR_VECTOR_CUBE_DUMMY):
             # No cube: no real data to return (in legacy style), so let's just return a `null` per geometry.
             return JSONResult(data=[None] * self.geometry_count())