diff --git a/dockercoins/hasher/Dockerfile b/dockercoins/hasher/Dockerfile
index 6313a131..707ecd12 100644
--- a/dockercoins/hasher/Dockerfile
+++ b/dockercoins/hasher/Dockerfile
@@ -1,7 +1,7 @@
 FROM ruby:alpine
 RUN apk add --update build-base curl
 RUN gem install sinatra --version '~> 3'
-RUN gem install thin
+RUN gem install thin --version '~> 1'
 ADD hasher.rb /
 CMD ["ruby", "hasher.rb"]
 EXPOSE 80