diff --git a/Dockerfile.release-tools b/Dockerfile.release-tools
index 13a828c..9659cd4 100644
--- a/Dockerfile.release-tools
+++ b/Dockerfile.release-tools
@@ -1,6 +1,6 @@
 FROM ruby:2.4-alpine
 
-RUN apk add --update --no-cache build-base cmake git openssh-client
+RUN apk add --update --no-cache build-base cmake git openssh-client openssl-dev
 
 # Set UTF-8 http://jaredmarkell.com/docker-and-locales/
 ENV LANG en_US.UTF-8