diff --git a/tests/test_pay.py b/tests/test_pay.py
index a3c21a4f3..81f0a7c49 100644
--- a/tests/test_pay.py
+++ b/tests/test_pay.py
@@ -5313,3 +5313,24 @@ def test_pay_middle_fail(node_factory, bitcoind, executor):
     # And that will fail upstream
     with pytest.raises(RpcError, match=r'WIRE_INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS'):
         l1.rpc.waitsendpay('00' * 32)
+
+
+@pytest.mark.xfail(strict=True)
+def test_sendpay_dual_amounts(node_factory):
+    """Test that handing *both* msatoshi and amount_msat to sendpay works"""
+    l1 = node_factory.get_node(options={'allow-deprecated-apis': True})
+
+    route = [{'amount_msat': 1011,
+              'msatoshi': 1011,
+              'id': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59',
+              'delay': 20,
+              'channel': '1x1x1'},
+             {'amount_msat': 1000,
+              'msatoshi': 1000,
+              'id': '035d2b1192dfba134e10e540875d366ebc8bc353d5aa766b80c090b39c3a5d885d',
+              'delay': 10,
+              'channel': '2x2x2'}]
+    l1.rpc.check("sendpay", route=route, payment_hash="00" * 32)
+
+    with pytest.raises(RpcError, match=r'No connection to first peer found'):
+        l1.rpc.sendpay(route=route, payment_hash="00" * 32)