diff --git a/tox.ini b/tox.ini
index c718129a..b5e86312 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@ skip_missing_interpreters = False
 
 [testenv]
 usedevelop = true
+install_command = python -m pip install --no-use-pep517 {opts} {packages}
 commands =
     coverage run {envbindir}/zope-testrunner --test-path=src []
 extras = test