diff --git a/Dockerfile b/Dockerfile
index c74158d..efb59a3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,7 +7,8 @@ VOLUME /srv/slate/source
 
 EXPOSE 4567
 
-COPY . /srv/slate
+COPY Gemfile .
+COPY Gemfile.lock .
 
 RUN apt-get update \
     && apt-get install -y --no-install-recommends \
@@ -17,8 +18,11 @@ RUN apt-get update \
     && bundle install \
     && apt-get remove -y build-essential \
     && apt-get autoremove -y \
-    && rm -rf /var/lib/apt/lists/* \
-    && chmod +x /srv/slate/slate.sh
+    && rm -rf /var/lib/apt/lists/*
+
+COPY . /srv/slate
+
+RUN chmod +x /srv/slate/slate.sh
 
 ENTRYPOINT ["/srv/slate/slate.sh"]
 CMD ["build"]