diff --git a/docker/ci/Dockerfile b/docker/ci/Dockerfile
index d51cc399..ac84c795 100644
--- a/docker/ci/Dockerfile
+++ b/docker/ci/Dockerfile
@@ -1,7 +1,10 @@
 FROM quay.io/podman/stable
 
 RUN dnf -y install git openssl
 
 COPY init.sh /init.sh
 
+ENV GIT_REF=master
+ENV GIT_REMOTE=https://git.kolab.org/source/kolab.git
+
 CMD [ "/init.sh" ]
diff --git a/docker/ci/init.sh b/docker/ci/init.sh
index 0c2f1f0d..f3098fb7 100755
--- a/docker/ci/init.sh
+++ b/docker/ci/init.sh
@@ -1,5 +1,14 @@
 #!/bin/bash
 set -e
-git clone https://git.kolab.org/source/kolab.git
+function checkout() {
+    if [ ! -d "$1" ]; then
+        git clone "$2" "$1"
+        pushd "$1"
+        git checkout "$3" 
+        popd
+    fi
+}
+
+checkout kolab $GIT_REMOTE $GIT_REF
 pushd kolab
 ci/testctl testrun