diff --git a/Dockerfile b/Dockerfile
index 748681f8f11772a142e6c68c0f2396d8ba6f060a..66bfcb4c05e0919d33cc4d19b5200d408e6e9acc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,8 @@
 FROM debian:stretch
 ENV DEBIAN_FRONTEND noninteractive
 RUN apt-get update && \
-    apt-get install -y knot-dnsutils knot-host knot-resolver dma bsd-mailx
+    apt-get install -y knot-dnsutils knot-host knot-resolver dma bsd-mailx && \
+    rm -rf /tmp/* /var/tmp/* /var/lib/apt/lists/* /var/cache/apt/archives/*
 COPY entrypoint.sh /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]
 CMD ["/bin/bash", "--login"]