diff --git a/tests/dockerfile b/tests/dockerfile
index b215db7a..40152059 100644
--- a/tests/dockerfile
+++ b/tests/dockerfile
@@ -1,4 +1,5 @@
 FROM ubuntu:18.04
+ENV DEBIAN_FRONTEND=noninteractive
 MAINTAINER Matthias Hochsteger <matthias.hochsteger@tuwien.ac.at>
 RUN apt-get update && apt-get -y install python3 libpython3-dev libxmu-dev tk-dev tcl-dev cmake git g++ libglu1-mesa-dev ccache python3-pytest python3-numpy python3-tk clang-tidy
 ADD . /root/src/netgen