diff --git a/example/animal-service/Gemfile b/example/animal-service/Gemfile
index db639d15..0f3c5b42 100644
--- a/example/animal-service/Gemfile
+++ b/example/animal-service/Gemfile
@@ -7,7 +7,7 @@ group :development, :test do
 end
 
 gem 'rake'
-gem 'rack', '~> 2.2', '>= 2.2.6.4'
+gem 'rack', '~> 2.2', '>= 2.2.8.1'
 gem 'sqlite3'
 gem 'sequel'
-gem 'sinatra'
+gem 'sinatra', '>= 3.1.0'