diff --git a/Gemfile b/Gemfile
index 351033344..b6d7fadb0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,3 +5,4 @@ source 'https://rubygems.org'
 gemspec
 
 gem "ruby-lsp", "~> 0.2.0", :group => :development
+gem "mocha", "~> 2.1.0"