diff --git a/.travis.yml b/.travis.yml
index 8b718d72..93a5935f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 dist: xenial
-# services:
-#   - xvfb
+services:
+  - xvfb
 language: python
 sudo: required
 addons:
@@ -11,12 +11,12 @@ python:
   - "3.7"
 install:
   - pip install -r requirements.txt
-# - pip install pytest-faulthandler
+  - pip install pytest-faulthandler
   - pip install pytest-cov
-# - pip install pytest-qt
+  - pip install pytest-qt
   - pip install codecov
 script:
-# - xvfb-run -a python -m pytest --cov=nw -m "project|core|gui" -v -s
-  - python -m pytest --cov=nw -m "project|core" -v
+  - xvfb-run -a python -m pytest --cov=nw -m "project|core|gui" -v -s
+# - python -m pytest --cov=nw -m "project|core" -v
 after_success:
   - codecov
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 00000000..17f2ac93
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,6 @@
+[pytest]
+markers =
+    project: Project classes tests
+    core: Core functionality tests
+    gui: Qt5 GUI tests
+    serial
diff --git a/tests/test_gui.py b/tests/test_gui.py
index 92c0d7c5..5f91550c 100644
--- a/tests/test_gui.py
+++ b/tests/test_gui.py
@@ -14,8 +14,8 @@ testRef   = path.join(testDir,"reference")
 
 @pytest.mark.gui
 def testMainWindows(qtbot, tmpdir):
-    confDir = tmpdir.mkdir("conf")
-    projDir = tmpdir.mkdir("project")
+    confDir = str(tmpdir.mkdir("conf"))
+    projDir = str(tmpdir.mkdir("project"))
     nwGUI = nw.main(["--testmode","--config=%s" % confDir])
     qtbot.addWidget(nwGUI)
     nwGUI.show()
@@ -103,9 +103,9 @@ def testMainWindows(qtbot, tmpdir):
     qtbot.wait(stepDelay)
 
     # Check the files
-    projFile = projDir.join("nwProject.nwx")
+    projFile = str(projDir.join("nwProject.nwx"))
     assert cmpFiles(projFile, path.join(testRef,"gui_nwProject.nwx"), [2])
-    sceneFile = projDir.join("data_3","1489056e0916_main.nwd")
+    sceneFile = str(projDir.join("data_3","1489056e0916_main.nwd"))
     assert cmpFiles(sceneFile, path.join(testRef,"gui_1489056e0916_main.nwd"))
 
     # qtbot.stopForInteraction()