diff --git a/t/Dockerfile b/t/Dockerfile
index b5aa2a7..57f6b27 100644
--- a/t/Dockerfile
+++ b/t/Dockerfile
@@ -4,8 +4,9 @@ MAINTAINER Jessica Frazelle <jess@docker.com>
 RUN apk update && apk add \
 	build-base \
 	ca-certificates \
+	ruby \
 	ruby-dev \
 	&& rm -rf /var/cache/apk/* \
-	&& gem install t
+	&& gem install --no-document t
 
 ENTRYPOINT [ "t" ]