diff --git a/Makefile b/Makefile
index e107ec0ac163ff4c778adcd84137c7142428f6d9..42a8a430671f9464101ba0799bb6ac4e4f35be20 100644
--- a/Makefile
+++ b/Makefile
@@ -61,7 +61,7 @@ test-all: ## run tests on every Python version with tox
 	tox
 
 coverage: ## check code coverage quickly with the default Python
-	xvfb-run coverage run --source flatland -m pytest
+	xvfb-run -a coverage run --source flatland -m pytest
 	coverage report -m
 	coverage html
 	$(BROWSER) htmlcov/index.html
diff --git a/tox.ini b/tox.ini
index 768d58db5192cb2a7363fc68ef3392842556479d..5a677e76fd79f1e87369b59ee2b24ed6cfe5783d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py36, py37, flake8, docs, coverage
+envlist = py36, py37, flake8, docs, coverage, xvfb-run, sh
 
 [travis]
 python =
@@ -36,6 +36,6 @@ deps =
 commands =
     pip install -U pip
     sh -c 'echo DISPLAY: $DISPLAY'
-    xvfb-run py.test --basetemp={envtmpdir}
+    xvfb-run -a py.test --basetemp={envtmpdir}