diff --git a/Jenkinsfile b/Jenkinsfile
index 9110b48..cae16b4 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -12,7 +12,7 @@ pipeline {
                 sh "mkdir ${env.TMPDIR}"
                 sh """
 /usr/bin/python3 -m venv ${env.TMPDIR}/venv/
-${env.TMPDIR}/venv/bin/pip install tox
+${env.TMPDIR}/venv/bin/pip install "tox<4"
 PGPORT=`python3 -c 'import struct; import socket; s=socket.socket(); s.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, struct.pack("ii", 1, 0)); s.bind(("", 0)); print(s.getsockname()[1]); s.close()'` pg_virtualenv -o fsync=off ${env.TMPDIR}/venv/bin/tox -r"""
             }
             post {