diff --git a/tests/unit_tests/test_deplete_integrator.py b/tests/unit_tests/test_deplete_integrator.py
index c22f075aa3..a08d8738c5 100644
--- a/tests/unit_tests/test_deplete_integrator.py
+++ b/tests/unit_tests/test_deplete_integrator.py
@@ -14,7 +14,6 @@ import numpy as np
 from uncertainties import ufloat
 import pytest
 
-from openmc import Material
 from openmc.mpi import comm
 from openmc.deplete import (
     ReactionRates, Results, ResultsList, OperatorResult, PredictorIntegrator,
@@ -180,11 +179,8 @@ def test_integrator(run_in_tmpdir, scheme):
     res = ResultsList.from_hdf5(
         operator.output_dir / "depletion_results.h5")
 
-    mat = Material()
-    mat.id = 1
-
-    t1, y1 = res.get_atoms(mat, "1")
-    t2, y2 = res.get_atoms(mat, "2")
+    t1, y1 = res.get_atoms("1", "1")
+    t2, y2 = res.get_atoms("1", "2")
 
     assert (t1 == [0.0, 0.75, 1.5]).all()
     assert y1 == pytest.approx(bundle.atoms_1)
diff --git a/tests/unit_tests/test_deplete_restart.py b/tests/unit_tests/test_deplete_restart.py
index f396a8b8f0..82ef05ac7b 100644
--- a/tests/unit_tests/test_deplete_restart.py
+++ b/tests/unit_tests/test_deplete_restart.py
@@ -87,11 +87,8 @@ def test_restart(run_in_tmpdir, scheme):
     results = openmc.deplete.ResultsList.from_hdf5(
         operator.output_dir / "depletion_results.h5")
 
-    mat = openmc.Material()
-    mat.id = 1
-
-    _t, y1 = results.get_atoms(mat, "1")
-    _t, y2 = results.get_atoms(mat, "2")
+    _t, y1 = results.get_atoms("1", "1")
+    _t, y2 = results.get_atoms("1", "2")
 
     assert y1 == pytest.approx(bundle.atoms_1)
     assert y2 == pytest.approx(bundle.atoms_2)
diff --git a/tests/unit_tests/test_deplete_resultslist.py b/tests/unit_tests/test_deplete_resultslist.py
index 96bbcab778..bcce45769f 100644
--- a/tests/unit_tests/test_deplete_resultslist.py
+++ b/tests/unit_tests/test_deplete_resultslist.py
@@ -21,7 +21,7 @@ def test_get_atoms(res):
     mat = openmc.Material()
     mat.id = 1
 
-    t, n = res.get_atoms(mat, "Xe135")
+    t, n = res.get_atoms("1", "Xe135")
 
     t_ref = np.array([0.0, 1296000.0, 2592000.0, 3888000.0])
     n_ref = np.array(
@@ -33,24 +33,22 @@ def test_get_atoms(res):
     # Check alternate units
     volume = res[0].volume["1"]
 
-    t_days, n_cm3 = res.get_atoms(mat, "Xe135", nuc_units="atom/cm3", time_units="d")
+    t_days, n_cm3 = res.get_atoms("1", "Xe135", nuc_units="atom/cm3", time_units="d")
 
     assert t_days == pytest.approx(t_ref / (60 * 60 * 24))
     assert n_cm3 == pytest.approx(n_ref / volume)
 
-    t_min, n_bcm = res.get_atoms(mat, "Xe135", nuc_units="atom/b-cm", time_units="min")
+    t_min, n_bcm = res.get_atoms("1", "Xe135", nuc_units="atom/b-cm", time_units="min")
     assert n_bcm == pytest.approx(n_cm3 * 1e-24)
     assert t_min == pytest.approx(t_ref / 60)
 
-    t_hour, _n = res.get_atoms(mat, "Xe135", time_units="h")
+    t_hour, _n = res.get_atoms("1", "Xe135", time_units="h")
     assert t_hour == pytest.approx(t_ref / (60 * 60))
 
 
 def test_get_reaction_rate(res):
     """Tests evaluating reaction rate."""
-    mat = openmc.Material()
-    mat.id = 1
-    t, r = res.get_reaction_rate(mat, "Xe135", "(n,gamma)")
+    t, r = res.get_reaction_rate("1", "Xe135", "(n,gamma)")
 
     t_ref = [0.0, 1296000.0, 2592000.0, 3888000.0]
     n_ref = [6.67473282e+08, 3.72442707e+14, 3.61129692e+14, 4.01920099e+14]