diff --git a/.travis.yml b/.travis.yml
index 16f466403c..c9aaf375f0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -41,7 +41,7 @@ before_script:
 
 script:
     - python setup.py install
-    - make stylecheck
+    - if [ $TRAVIS_PYTHON_VERSION == 3.6 ]; then make stylecheck; fi
     - tox
 
 notifications:
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 494ad11d4e..11e0a245c8 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -5,5 +5,5 @@ mock>=2.0.0
 flake8
 protobuf
 isort
-black
+black; python_version >= "3.6"
 autoflake
diff --git a/setup.cfg b/setup.cfg
index bbeaa43f4e..3775b6d623 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -31,3 +31,4 @@ force_grid_wrap = 0
 combine_as_imports = True
 line_length = 88
 not_skip=__init__.py
+known_first_party=trezorlib