diff --git a/Dockerfile b/Dockerfile
index 2727d78..b7a0939 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 FROM debian:jessie
 RUN apt-get update --fix-missing
-RUN apt-get upgrade
+RUN apt-get upgrade -y
 RUN apt-get install -y python build-essential cmake git-core graphicsmagick imagemagick wget libfreetype6 \
   libfontconfig bzip2 curl libtheora0 poppler-utils unzip zip libav-tools libavcodec-extra \
   checkinstall libmad0-dev libsndfile1-dev libgd2-xpm-dev libboost-filesystem-dev libboost-program-options-dev libboost-regex-dev libid3tag0-dev libid3tag0
@@ -52,4 +52,4 @@ RUN curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-
   && ln -s /usr/local/bin/node /usr/local/bin/nodejs
 
 RUN apt-get clean
-RUN rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /deps
\ No newline at end of file
+RUN rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /deps