diff --git a/cirq/sim/density_matrix_simulator_test.py b/cirq/sim/density_matrix_simulator_test.py
index 58f1541d549..213932eb408 100644
--- a/cirq/sim/density_matrix_simulator_test.py
+++ b/cirq/sim/density_matrix_simulator_test.py
@@ -527,6 +527,25 @@ def test_simulate_qudits(dtype: Type[np.number], split: bool):
     assert len(result.measurements) == 0
 
 
+@pytest.mark.parametrize('dtype', [np.complex64, np.complex128])
+@pytest.mark.parametrize('split', [True, False])
+def test_reset_one_qubit_does_not_affect_partial_trace_of_other_qubits(
+    dtype: Type[np.number], split: bool
+):
+    q0, q1 = cirq.LineQubit.range(2)
+    simulator = cirq.DensityMatrixSimulator(dtype=dtype, split_untangled_states=split)
+    circuit = cirq.Circuit(
+        cirq.H(q0),
+        cirq.CX(q0, q1),
+        cirq.reset(q0),
+    )
+    result = simulator.simulate(circuit)
+    expected = np.zeros((4, 4), dtype=dtype)
+    expected[0, 0] = 0.5
+    expected[1, 1] = 0.5
+    np.testing.assert_almost_equal(result.final_density_matrix, expected)
+
+
 @pytest.mark.parametrize(
     'dtype,circuit',
     itertools.product(