diff --git a/tox.ini b/tox.ini
index af8217b..2c5a133 100644
--- a/tox.ini
+++ b/tox.ini
@@ -49,6 +49,7 @@
 # This target disables coverage on pypy because of performance problems with
 # coverage.py on pypy.
 [testenv:pypy-nocoverage]
+basepython = pypy
 commands =
     pip list
     python -c "from cryptography.hazmat.backends.openssl.backend import backend; print(backend.openssl_version_text())"