diff --git a/Dockerfile b/Dockerfile
index 4399f329..4e286104 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,7 @@
 FROM resin/rpi-buildstep:v0.0.3
 ADD . /app
 ADD deploy_key /root/.ssh/id_rsa
+RUN chmod 400 /root/.ssh/id_rsa
 ADD known_hosts /root/.ssh/known_hosts
 RUN /build/builder
 ENTRYPOINT ["/app/entry.sh"]