diff --git a/Makefile b/Makefile
index e1d45554..70f09ad9 100644
--- a/Makefile
+++ b/Makefile
@@ -2,9 +2,9 @@ all: init test
 
 init:
 	python setup.py develop
-	# pip install tox coverage<5
+	pip install tox "coverage<5"
 
 test:
 	coverage erase
-	tox --parallel
+	tox --parallel--safe-build
 	coverage html