diff --git a/.ruby-version b/.ruby-version
index 35d16fb..ecd7ee5 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.5.7
+2.5.8
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 4345fd3..25dd809 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -8,9 +8,9 @@ There are a couple ways you can help improve webmention-cli:
 
 ## Getting Started
 
-webmention-cli is developed using Ruby 2.5.7 and is additionally tested against Ruby 2.6 and 2.7 using [Travis CI](https://travis-ci.com/jgarber623/webmention-cli).
+webmention-cli is developed using Ruby 2.5.8 and is additionally tested against Ruby 2.6 and 2.7 using [Travis CI](https://travis-ci.com/jgarber623/webmention-cli).
 
-Before making changes to webmention-cli, you'll want to install Ruby 2.5.7. It's recommended that you use a Ruby version managment tool like [rbenv](https://github.com/rbenv/rbenv), [chruby](https://github.com/postmodern/chruby), or [rvm](https://github.com/rvm/rvm). Once you've installed Ruby 2.5.7 using your method of choice, install the project's gems by running:
+Before making changes to webmention-cli, you'll want to install Ruby 2.5.8. It's recommended that you use a Ruby version managment tool like [rbenv](https://github.com/rbenv/rbenv), [chruby](https://github.com/postmodern/chruby), or [rvm](https://github.com/rvm/rvm). Once you've installed Ruby 2.5.8 using your method of choice, install the project's gems by running:
 
 ```sh
 bundle install
diff --git a/README.md b/README.md
index a5ce37c..9288d07 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@
 
 Before installing and using webmention-cli, you'll want to have [Ruby](https://www.ruby-lang.org) 2.5 (or newer) installed. It's recommended that you use a Ruby version managment tool like [rbenv](https://github.com/rbenv/rbenv), [chruby](https://github.com/postmodern/chruby), or [rvm](https://github.com/rvm/rvm).
 
-webmention-cli is developed using Ruby 2.5.7 and is additionally tested against Ruby 2.6 and 2.7 using [Travis CI](https://travis-ci.com/jgarber623/webmention-cli).
+webmention-cli is developed using Ruby 2.5.8 and is additionally tested against Ruby 2.6 and 2.7 using [Travis CI](https://travis-ci.com/jgarber623/webmention-cli).
 
 ## Installation