diff --git a/deploy/rails-prod-Dockerfile b/deploy/rails-prod-Dockerfile
index 05a2297..1a5a659 100644
--- a/deploy/rails-prod-Dockerfile
+++ b/deploy/rails-prod-Dockerfile
@@ -3,7 +3,6 @@ FROM ubuntu:xenial
 HEALTHCHECK --start-period=30s CMD curl --insecure https://127.0.0.1/
 
 ENV RUBY_VERSION=2.5.1
-ENV RUBY_MAJOR_VERSION=2.5
 
 ENV TINI_VERSION v0.18.0
 ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
@@ -37,7 +36,7 @@ RUN apt-get -qq update \
     lsb-release \
     dirmngr \
     gnupg \
-  && wget http://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR_VERSION}/ruby-${RUBY_VERSION}.tar.gz \
+  && wget http://cache.ruby-lang.org/pub/ruby/$(echo $RUBY_VERSION | cut -d '.' -f 1,2)/ruby-${RUBY_VERSION}.tar.gz \
   && tar -xzf ruby-${RUBY_VERSION}.tar.gz \
   && cd ruby-${RUBY_VERSION} \
   && ./configure \