diff --git a/Dockerfile b/Dockerfile
index 8f979b3..4392b08 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 FROM mono:slim
 
 RUN apt-get update -y && apt-get upgrade -y
-RUN apt-get install -y mono-complete gtk-sharp2 nuget capnproto git ruby
+RUN apt-get install -y mono-complete gtk-sharp2 nuget capnproto git ruby ruby-dev
 RUN gem install bundler