diff --git a/CHANGELOG.md b/CHANGELOG.md
index 33acea97..6975cf73 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 
 ## Changes since v6.0.0
 
+- [#675](https://github.com/oauth2-proxy/oauth2-proxy/pull/675) Fix required ruby version and deprecated option for building docs (@mkontani)
 - [#669](https://github.com/oauth2-proxy/oauth2-proxy/pull/669) Reduce docker context to improve build times (@JoelSpeed)
 - [#668](https://github.com/oauth2-proxy/oauth2-proxy/pull/668) Use req.Host in --force-https when req.URL.Host is empty (@zucaritask)
 - [#660](https://github.com/oauth2-proxy/oauth2-proxy/pull/660) Use builder pattern to simplify requests to external endpoints (@JoelSpeed)
diff --git a/docs/Makefile b/docs/Makefile
index 1824ba08..40e32bdd 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -1,7 +1,7 @@
 .PHONY: ruby
 ruby:
 	@ if [ ! $$(which ruby) ]; then \
-			echo "Please install ruby version 2.1.0 or higher"; \
+			echo "Please install ruby version 2.5.0 or higher"; \
 		fi
 
 .PHONY: bundle
@@ -11,7 +11,8 @@ bundle: ruby
 		fi
 
 vendor/bundle: bundle
-	bundle install --path vendor/bundle
+	bundle config set --local path 'vendor/bundle'
+	bundle install
 
 .PHONY: serve
 serve: vendor/bundle
diff --git a/docs/README.md b/docs/README.md
index cb133d3f..77a544ce 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -9,5 +9,5 @@ When making changes to this docs site, please test your changes locally:
 docs$ make serve
 ```
 
-To run the docs site locally you will need Ruby at version 2.1.0 or
+To run the docs site locally you will need Ruby at version 2.5.0 or
 higher and `bundle` (`gem install bundler` if you already have Ruby).