diff --git a/trezorlib/tests/device_tests/test_msg_signtx.py b/trezorlib/tests/device_tests/test_msg_signtx.py
index 7b92325aa..25181fe43 100644
--- a/trezorlib/tests/device_tests/test_msg_signtx.py
+++ b/trezorlib/tests/device_tests/test_msg_signtx.py
@@ -16,7 +16,10 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
-from .common import *
+from binascii import hexlify, unhexlify
+import pytest
+
+from .common import TrezorTest
 
 from trezorlib import coins
 from trezorlib import messages as proto
@@ -514,12 +517,9 @@ class TestMsgSigntx(TrezorTest):
                 proto.Failure(code=proto.FailureType.NotEnoughFunds)
             ])
 
-            try:
+            with pytest.raises(CallException) as exc:
                 self.client.sign_tx('Bitcoin', [inp1, ], [out1, ])
-            except CallException as e:
-                assert e.args[0] == proto.FailureType.NotEnoughFunds
-            else:
-                assert False  # types.FailureType.NotEnoughFunds expected
+            assert exc.value.args[0] == proto.FailureType.NotEnoughFunds
 
     def test_p2sh(self):
         self.setup_mnemonic_nopin_nopassphrase()
@@ -623,13 +623,10 @@ class TestMsgSigntx(TrezorTest):
         assert hexlify(serialized_tx) == b'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'
 
         # Now run the attack, must trigger the exception
-        try:
+        with pytest.raises(CallException) as exc:
             self.client.sign_tx('Bitcoin', [inp1, inp2], [out1, out2], debug_processor=attack_processor)
-        except CallException as exc:
-            assert exc.args[0] == proto.FailureType.ProcessError
-            assert exc.args[1] == 'Transaction has changed during signing'
-        else:
-            assert False  # exception expected
+        assert exc.value.args[0] == proto.FailureType.ProcessError
+        assert exc.value.args[1] == 'Transaction has changed during signing'
 
     def test_attack_change_input_address(self):
         # This unit test attempts to modify input address after the Trezor checked
@@ -701,13 +698,10 @@ class TestMsgSigntx(TrezorTest):
                 proto.Failure(code=proto.FailureType.ProcessError),
             ])
             # Now run the attack, must trigger the exception
-            try:
+            with pytest.raises(CallException) as exc:
                 self.client.sign_tx('Testnet', [inp1], [out1, out2], debug_processor=attack_processor)
-            except CallException as exc:
-                assert exc.args[0] == proto.FailureType.ProcessError
-                assert exc.args[1] == 'Transaction has changed during signing'
-            else:
-                assert False  # exception expected
+            assert exc.value.args[0] == proto.FailureType.ProcessError
+            assert exc.value.args[1] == 'Transaction has changed during signing'
 
     def test_spend_coinbase(self):
         # 25 TEST generated to m/1 (mfiGQVPcRcaEvQPYDErR34DcCovtxYvUUV)
diff --git a/trezorlib/tests/device_tests/test_msg_signtx_bcash.py b/trezorlib/tests/device_tests/test_msg_signtx_bcash.py
index f397d5b6a..f54cedb45 100644
--- a/trezorlib/tests/device_tests/test_msg_signtx_bcash.py
+++ b/trezorlib/tests/device_tests/test_msg_signtx_bcash.py
@@ -222,13 +222,10 @@ class TestMsgSigntxBch(TrezorTest):
                 proto.Failure(code=proto.FailureType.ProcessError),
             ])
 
-            try:
+            with pytest.raises(CallException) as exc:
                 self.client.sign_tx('Bcash', [inp1, inp2], [out1], debug_processor=attack_processor)
-            except CallException as exc:
-                assert exc.args[0] == proto.FailureType.ProcessError
-                assert exc.args[1] == 'Transaction has changed during signing'
-            else:
-                assert False  # exception expected
+            assert exc.value.args[0] == proto.FailureType.ProcessError
+            assert exc.value.args[1] == 'Transaction has changed during signing'
 
     def test_attack_change_input(self):
         self.setup_mnemonic_allallall()
diff --git a/trezorlib/tests/device_tests/test_msg_signtx_segwit.py b/trezorlib/tests/device_tests/test_msg_signtx_segwit.py
index 65136c3a3..edfffe019 100644
--- a/trezorlib/tests/device_tests/test_msg_signtx_segwit.py
+++ b/trezorlib/tests/device_tests/test_msg_signtx_segwit.py
@@ -15,8 +15,10 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
-from .common import *
+from binascii import hexlify, unhexlify
+import pytest
 
+from .common import TrezorTest
 from trezorlib import coins
 from trezorlib import messages as proto
 from trezorlib.ckd_public import deserialize
@@ -235,10 +237,7 @@ class TestMsgSigntxSegwit(TrezorTest):
                 proto.TxRequest(request_type=proto.RequestType.TXINPUT, details=proto.TxRequestDetailsType(request_index=0)),
                 proto.Failure(code=proto.FailureType.ProcessError),
             ])
-            try:
+            with pytest.raises(CallException) as exc:
                 self.client.sign_tx('Testnet', [inp1], [out1, out2], debug_processor=attack_processor)
-            except CallException as exc:
-                assert exc.args[0] == proto.FailureType.ProcessError
-                assert exc.args[1] == 'Transaction has changed during signing'
-            else:
-                assert False  # exception expected
+            assert exc.value.args[0] == proto.FailureType.ProcessError
+            assert exc.value.args[1] == 'Transaction has changed during signing'
diff --git a/trezorlib/tests/device_tests/test_msg_stellar_verify_message.py b/trezorlib/tests/device_tests/test_msg_stellar_verify_message.py
index 30795c56b..f7ea1aa8c 100644
--- a/trezorlib/tests/device_tests/test_msg_stellar_verify_message.py
+++ b/trezorlib/tests/device_tests/test_msg_stellar_verify_message.py
@@ -13,12 +13,13 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
+from binascii import unhexlify
+import pytest
+
 from .common import TrezorTest
 from .conftest import TREZOR_VERSION
-from binascii import unhexlify, hexlify
 from trezorlib import messages as proto
 from trezorlib.client import CallException
-import pytest
 
 
 @pytest.mark.stellar
@@ -44,28 +45,19 @@ class TestMsgStellarVerifyMessage(TrezorTest):
         msg = 'abc'
         pubkey = unhexlify('15d648bfe4d36f196cfb5735ffd8ca54cd4b8233f743f22449de7cf301cdb469')
         signature = unhexlify('0000000000000000')  # invalid length
-        try:
+        with pytest.raises(CallException) as exc:
             self.client.stellar_verify_message(pubkey, signature, msg)
-        except CallException as exc:
-            assert exc.args[0] == proto.FailureType.DataError
-        else:
-            assert False
+        assert exc.value.args[0] == proto.FailureType.DataError
 
         # invalid signature
         signature = unhexlify('00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000')
-        try:
+        with pytest.raises(CallException) as exc:
             self.client.stellar_verify_message(pubkey, signature, msg)
-        except CallException as exc:
-            assert exc.args[0] == proto.FailureType.DataError
-        else:
-            assert False
+        assert exc.value.args[0] == proto.FailureType.DataError
 
         # invalid pubkey
         pubkey = unhexlify('00')
         signature = unhexlify('00')
-        try:
+        with pytest.raises(CallException) as exc:
             self.client.stellar_verify_message(pubkey, signature, msg)
-        except CallException as exc:
-            assert exc.args[0] == proto.FailureType.DataError
-        else:
-            assert False
+        assert exc.value.args[0] == proto.FailureType.DataError
diff --git a/trezorlib/tests/device_tests/test_multisig.py b/trezorlib/tests/device_tests/test_multisig.py
index 4316a9a71..15d263760 100644
--- a/trezorlib/tests/device_tests/test_multisig.py
+++ b/trezorlib/tests/device_tests/test_multisig.py
@@ -16,9 +16,10 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
-from __future__ import print_function
+from binascii import hexlify, unhexlify
+import pytest
 
-from .common import *
+from .common import TrezorTest
 from trezorlib import messages as proto
 import trezorlib.ckd_public as bip32
 from trezorlib.client import CallException
@@ -249,10 +250,8 @@ class TestMultisig(TrezorTest):
             script_type=proto.OutputScriptType.PAYTOADDRESS
         )
 
-        try:
+        with pytest.raises(CallException) as exc:
             self.client.sign_tx('Bitcoin', [inp1, ], [out1, ])
-        except CallException as exc:
-            assert exc.args[0] == proto.FailureType.DataError
-            assert exc.args[1] == 'Pubkey not found in multisig script'
-        else:
-            assert False  # exception expected
+
+        assert exc.value.args[0] == proto.FailureType.DataError
+        assert exc.value.args[1] == 'Pubkey not found in multisig script'
diff --git a/trezorlib/tests/device_tests/test_op_return.py b/trezorlib/tests/device_tests/test_op_return.py
index e4a38bdc9..1168a128c 100644
--- a/trezorlib/tests/device_tests/test_op_return.py
+++ b/trezorlib/tests/device_tests/test_op_return.py
@@ -15,8 +15,10 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with this library.  If not, see <http://www.gnu.org/licenses/>.
+from binascii import unhexlify, hexlify
+import pytest
 
-from .common import *
+from .common import TrezorTest
 
 from trezorlib import messages as proto
 from trezorlib.client import CallException
@@ -105,10 +107,8 @@ class TestOpReturn(TrezorTest):
                 proto.Failure()
             ])
 
-            try:
+            with pytest.raises(CallException) as exc:
                 self.client.sign_tx('Bitcoin', [inp1], [out1])
-            except CallException as exc:
-                assert exc.args[0] == proto.FailureType.DataError
-                assert exc.args[1] == 'OP_RETURN output with non-zero amount'
-            else:
-                assert False  # exception expected
+
+            assert exc.value.args[0] == proto.FailureType.DataError
+            assert exc.value.args[1] == 'OP_RETURN output with non-zero amount'