diff --git a/Dockerfile b/Dockerfile
index 095df49..3c52a0f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM debian
+FROM debian:stretch
 
 LABEL maintainer Knut Ahlers <knut@ahlers.me>
 
@@ -10,14 +10,15 @@ RUN set -ex \
  && apt-get update \
  && apt-get install -y curl bzip2 ca-certificates --no-install-recommends \
  && curl -sSfLo teamspeak3-server_linux-amd64.tar.bz2 \
-      http://dl.4players.de/ts/releases/${TEAMSPEAK_VERSION}/teamspeak3-server_linux_amd64-${TEAMSPEAK_VERSION}.tar.bz2 \
+      "http://dl.4players.de/ts/releases/${TEAMSPEAK_VERSION}/teamspeak3-server_linux_amd64-${TEAMSPEAK_VERSION}.tar.bz2" \
  && echo "${TEAMSPEAK_SHA256} *teamspeak3-server_linux-amd64.tar.bz2" | sha256sum -c - \
  && tar -C /opt -xjf teamspeak3-server_linux-amd64.tar.bz2 \
  && rm teamspeak3-server_linux-amd64.tar.bz2 \
  && apt-get purge -y curl bzip2 && apt-get autoremove -y \
- && rm -r /var/lib/apt/lists/*
+ && apt-get clean \
+ && rm -rf /var/lib/apt/lists/*
 
-ADD docker-ts3.sh /opt/docker-ts3.sh
+COPY docker-ts3.sh /opt/docker-ts3.sh
 
 # Inject a Volume for any TS3-Data that needs to be persisted or to be accessible from the host. (e.g. for Backups)
 VOLUME ["/teamspeak3"]