diff --git a/setup.cfg b/setup.cfg
index 25a748c4e..5c301c9d6 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -33,4 +33,4 @@ line_length = 88
 not_skip=__init__.py
 known_first_party=trezorlib
 known_third_party=hidapi, rlp, ethjsonrpc, ecdsa, mnemonic, requests, click, pyblake2, \
-    usb, construct
+    usb, construct, pytest, mock
diff --git a/trezorlib/tests/unit_tests/test_transport.py b/trezorlib/tests/unit_tests/test_transport.py
index 4dd1f941a..62f00fbb4 100644
--- a/trezorlib/tests/unit_tests/test_transport.py
+++ b/trezorlib/tests/unit_tests/test_transport.py
@@ -15,6 +15,7 @@
 # If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
 
 import mock
+
 from trezorlib.transport import all_transports