diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 05aa099..b0cbf3c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,5 +1,5 @@
 ---
-image: debian:buster
+image: s3lph/matemat:20180619-01
 
 stages:
 - test
@@ -8,21 +8,13 @@ stages:
 test:
   stage: test
   script:
-  - useradd matemat
-  - chmod o+rw -R .
-  - apt-get update -qy
-  - apt-get install -y --no-install-recommends python3-dev python3-pip python3-coverage python3-setuptools build-essential
-  - pip3 install wheel
   - pip3 install -r requirements.txt
-  - su - matemat -c 'python3-coverage run --branch -m unittest discover matemat'
+  - python3-coverage run --branch -m unittest discover matemat
   - python3-coverage report -m --include 'matemat/*' --omit '*/test_*.py'
 
 codestyle:
   stage: codestyle
   script:
-  - apt-get update -qy
-  - apt-get install -y --no-install-recommends python3-dev python3-pip python3-coverage python3-setuptools build-essential
-  - pip3 install wheel pycodestyle mypy
   - pip3 install -r requirements.txt
   - pycodestyle matemat
 #  - mypy --ignore-missing-imports --strict -p matemat
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..126a06f
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,10 @@
+
+FROM debian:buster
+
+RUN useradd -d /home/matemat -m matemat
+RUN apt-get update -qy
+RUN apt-get install -y --no-install-recommends python3-dev python3-pip python3-coverage python3-setuptools build-essential
+RUN pip3 install wheel pycodestyle mypy
+
+WORKDIR /home/matemat
+USER matemat