diff --git a/.travis.yml b/.travis.yml
index c9aaf375f0..d01ee6969d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,7 +19,6 @@ env:
         PROTOBUF_VERSION=3.4.0
 
 python:
-    - "3.3"
     - "3.4"
     - "3.5"
     - "3.6"
@@ -28,7 +27,6 @@ install:
     # Optimisation: build requirements as wheels, which get cached by Travis
     - pip install "pip>=9.0" wheel  # pip 9.0 understands `python_requires` constraints
     - pip install "setuptools>=38"  # setuptools >= 38 are capable of using prebuilt wheels
-    - pip install "virtualenv<16.0.0"  # virtualenv 16.0.0 drops support for py33 without properly declaring it
     - pip install tox-travis
     - pip install -r requirements-dev.txt
     # protobuf-related dependencies
diff --git a/tox.ini b/tox.ini
index 555a08680d..06c2b1d247 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,13 +10,10 @@ deps =
     -rrequirements-dev.txt
 commands =
     # Generate local files
-    python setup.py prebuild
+    python setup.py build
     # Working in the local directory, try to compile all bytecode
     python -m compileall trezorlib/
     # From installed version, smoke-test trezorctl
     trezorctl --help
-    # Run non-device-dependent tests
-    python -m pytest --pyarg trezorlib.tests.unit_tests
-    # This whole thing is a hack, as the tests run against the cwd version of
-    # python-trezor, as opposed to what is installed.
-    # A better solution would be to put `trezorlib` into `src`. But that's not done yet
+    # Run non-device-dependent tests from installed version
+    python -E -m pytest --pyarg trezorlib.tests.unit_tests