diff --git a/src/scida/customs/arepo/dataset.py b/src/scida/customs/arepo/dataset.py
index 80480fe..86f7850 100644
--- a/src/scida/customs/arepo/dataset.py
+++ b/src/scida/customs/arepo/dataset.py
@@ -1531,7 +1531,7 @@ def map_group_operation(
     # TODO: very messy and inefficient routine. improve some time.
     # TODO: Set entry_bytes_out
     nbytes_dtype_out = 4  # TODO: hardcode 4 byte output dtype as estimate for now
-    entry_nbytes_out = nbytes_dtype_out * np.product(shape)
+    entry_nbytes_out = nbytes_dtype_out * np.prod(shape)
 
     # list_chunkedges refers to bounds of index intervals to be processed together
     # if idxlist is specified, then these indices do not have to refer to group indices.
diff --git a/tests/test_simulation_units.py b/tests/test_simulation_units.py
index 96d04c7..51e352e 100644
--- a/tests/test_simulation_units.py
+++ b/tests/test_simulation_units.py
@@ -16,7 +16,7 @@ def test_simulation_tng50(testdatapath):
     # Compare dark matter mass
     cosmology: FlatLambdaCDM = snp.cosmology
     ureg = snp.unitregistry
-    vol = np.product(snp.boxsize) / cosmology.h**3 * ureg.kpc**3
+    vol = np.prod(snp.boxsize) / cosmology.h**3 * ureg.kpc**3
     dens = (cosmology.Om0 - cosmology.Ob0) * cosmology.critical_density0
     dens = dens.value * ureg(dens.unit.to_string("ogip"))
     boxmass = vol * dens