diff --git a/qsimcirq/qsim_circuit.py b/qsimcirq/qsim_circuit.py
index 9d33881ed..980698ce9 100644
--- a/qsimcirq/qsim_circuit.py
+++ b/qsimcirq/qsim_circuit.py
@@ -374,13 +374,11 @@ def _check_for_confusion_matrix(self):
             for _, op, _ in self.findall_operations_with_gate_type(cirq.MeasurementGate)
             if op.gate.confusion_map
         ]
-        for confusion_map in confusion_maps_on_measurement_gates:
-            for map_values in confusion_map.values():
-                if map_values:
-                    raise ValueError(
-                        "Confusion Matrices are not currently supported in Qsim. "
-                        "See https://github.com/quantumlib/Cirq/issues/6305 for latest status"
-                    )
+        if confusion_maps_on_measurement_gates:
+            raise ValueError(
+                "Confusion Matrices are not currently supported in Qsim. "
+                "See https://github.com/quantumlib/Cirq/issues/6305 for latest status"
+            )
 
     def translate_cirq_to_qsim(
         self, qubit_order: cirq.QubitOrderOrList = cirq.QubitOrder.DEFAULT
diff --git a/qsimcirq_tests/qsimcirq_test.py b/qsimcirq_tests/qsimcirq_test.py
index eb63dc4d6..dee80da3a 100644
--- a/qsimcirq_tests/qsimcirq_test.py
+++ b/qsimcirq_tests/qsimcirq_test.py
@@ -345,7 +345,9 @@ def test_confusion_matrix_exception():
     x, y = sympy.Symbol("x"), sympy.Symbol("y")
     prs = [{x: np.int64(0), y: np.int64(1)}]
     qsim_simulator = qsimcirq.QSimSimulator()
-    with pytest.raises(ValueError):
+    with pytest.raises(
+        ValueError, match="Confusion Matrices are not currently supported"
+    ):
         _ = qsim_simulator.simulate_sweep(circuit, params=prs)