diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 72bd21c..5bfad1b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,5 +1,5 @@
 ---
-image: s3lph/matemat-ci:20180711-02
+image: s3lph/matemat-ci:20180720-01
 
 stages:
 - test
diff --git a/Dockerfile b/Dockerfile
index 83514a4..d084dfb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,6 +2,7 @@
 FROM python:3.6-alpine
 
 RUN mkdir -p /var/matemat/db /var/matemat/upload
+RUN apk add libmagic=5.33-r0
 ADD . /
 RUN pip3 install -r /requirements.txt
 
diff --git a/testing/Dockerfile b/testing/Dockerfile
index c51e01b..94644e6 100644
--- a/testing/Dockerfile
+++ b/testing/Dockerfile
@@ -5,7 +5,7 @@ RUN useradd -d /home/matemat -m matemat
 RUN mkdir -p /var/matemat/db && chown matemat:matemat -R /var/matemat/db
 RUN mkdir -p /var/matemat/upload && chown matemat:matemat -R /var/matemat/upload
 RUN apt-get update -qy
-RUN apt-get install -y --no-install-recommends sudo openssh-client git docker.io python3-dev python3-pip python3-coverage python3-setuptools build-essential
+RUN apt-get install -y --no-install-recommends file sudo openssh-client git docker.io python3-dev python3-pip python3-coverage python3-setuptools build-essential
 RUN pip3 install wheel pycodestyle mypy
 
 WORKDIR /home/matemat