diff --git a/trezorlib/tests/device_tests/test_msg_signtx.py b/trezorlib/tests/device_tests/test_msg_signtx.py
index 3aed470..fc32244 100644
--- a/trezorlib/tests/device_tests/test_msg_signtx.py
+++ b/trezorlib/tests/device_tests/test_msg_signtx.py
@@ -733,3 +733,54 @@ class TestMsgSigntx(TrezorTest):
 
         # Accepted by network: tx
         assert hexlify(serialized_tx) == b'010000000136825bfdb78c8ede226c7c4f25a018e99a2c061d63c7fb425fca7c7d6721dad6000000006a473044022047845c366eb24f40be315c7815a154513c444c7989eb80f7ce7ff6aeb703d26a022007c1f5efadf67c5889634fd7ac39a7ce78bffac291673e8772ecd8389c901d9f01210338d78612e990f2eea0c426b5e48a8db70b9d7ed66282b3b26511e0b1c75515a6ffffffff01c6100795000000001976a9143d2496e67f5f57a924353da42d4725b318e7a8ea88ac00000000'
+
+    def test_two_changes(self):
+        self.setup_mnemonic_allallall()
+        # see 87be0736f202f7c2bff0781b42bad3e0cdcb54761939da69ea793a3735552c56
+
+        # tx: e5040e1bc1ae7667ffb9e5248e90b2fb93cd9150234151ce90e14ab2f5933bcd
+        # input 0: 0.31 BTC
+        inp1 = proto.TxInputType(
+            address_n=self.client.expand_path("44'/1'/0'/0/0"),
+            # amount=31000000,
+            prev_hash=TXHASH_e5040e,
+            prev_index=0,
+        )
+
+        out1 = proto.TxOutputType(
+            address='msj42CCGruhRsFrGATiUuh25dtxYtnpbTx',
+            amount=30090000,
+            script_type=proto.OutputScriptType.PAYTOADDRESS,
+        )
+
+        out_change1 = proto.TxOutputType(
+            address_n=self.client.expand_path("44'/1'/0'/1/0"),
+            amount=900000,
+            script_type=proto.OutputScriptType.PAYTOADDRESS,
+        )
+
+        out_change2 = proto.TxOutputType(
+            address_n=self.client.expand_path("44'/1'/0'/1/1"),
+            amount=10000,
+            script_type=proto.OutputScriptType.PAYTOADDRESS,
+        )
+
+        with self.client:
+            self.client.set_tx_api(TxApiTestnet)
+            self.client.set_expected_responses([
+                proto.TxRequest(request_type=proto.RequestType.TXINPUT, details=proto.TxRequestDetailsType(request_index=0)),
+                proto.TxRequest(request_type=proto.RequestType.TXMETA, details=proto.TxRequestDetailsType(tx_hash=TXHASH_e5040e)),
+                proto.TxRequest(request_type=proto.RequestType.TXINPUT, details=proto.TxRequestDetailsType(request_index=0, tx_hash=TXHASH_e5040e)),
+                proto.TxRequest(request_type=proto.RequestType.TXOUTPUT, details=proto.TxRequestDetailsType(request_index=0, tx_hash=TXHASH_e5040e)),
+                proto.TxRequest(request_type=proto.RequestType.TXOUTPUT, details=proto.TxRequestDetailsType(request_index=1, tx_hash=TXHASH_e5040e)),
+                proto.TxRequest(request_type=proto.RequestType.TXOUTPUT, details=proto.TxRequestDetailsType(request_index=0)),
+                proto.ButtonRequest(code=proto.ButtonRequestType.ConfirmOutput),
+                proto.TxRequest(request_type=proto.RequestType.TXOUTPUT, details=proto.TxRequestDetailsType(request_index=1)),
+                proto.TxRequest(request_type=proto.RequestType.TXOUTPUT, details=proto.TxRequestDetailsType(request_index=2)),
+
+                # error should occur
+                proto.Failure(code=proto.FailureType.ProcessError, message='Only one change output is valid'),
+            ])
+
+            with pytest.raises(CallException):
+                self.client.sign_tx('Testnet', [inp1, ], [out1, out_change1, out_change2])