diff --git a/concourse_unit_test_task b/concourse_unit_test_task
index 1ee9526f87b..e46d4ce7842 100644
--- a/concourse_unit_test_task
+++ b/concourse_unit_test_task
@@ -1,8 +1,9 @@
 export DEBIAN_FRONTEND=noninteractive && \
 apt-get update && \
-apt-get install -y build-essential python3-pip python3-dev git libpcre++-dev gettext libpq-dev && \
-pip install -U pip && \
-pip install tox && \
+apt-get install -y build-essential python3-pip python3-dev python3-venv git gettext libpq-dev && \
+python3 -m venv --system-site-packages /tmp/venv && \
+. /tmp/venv/bin/activate && \
+pip install -U tox && \
 cd source && \
-export UPPER_CONSTRAINTS_FILE=https://raw.githubusercontent.com/sapcc/requirements/stable/xena-m3/upper-constraints.txt && \
-tox -e pep8,py
+export TOX_CONSTRAINTS_FILE=https://raw.githubusercontent.com/sapcc/requirements/stable/2025.1-m3/upper-constraints.txt && \
+tox -e pep8,unit