diff --git a/expression-ruby/Rakefile b/expression-ruby/Rakefile
index 45da191..d9b45e0 100644
--- a/expression-ruby/Rakefile
+++ b/expression-ruby/Rakefile
@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 require 'rb_sys/extensiontask'
+require 'bundler/gem_tasks'
+require 'rspec/core/rake_task'
+
+RSpec::Core::RakeTask.new(:spec)
 
 GEMSPEC = Gem::Specification.load('lago-expression.gemspec')
 
diff --git a/expression-ruby/ext/lago_expression/src/lib.rs b/expression-ruby/ext/lago_expression/src/lib.rs
index 38783af..8669b93 100644
--- a/expression-ruby/ext/lago_expression/src/lib.rs
+++ b/expression-ruby/ext/lago_expression/src/lib.rs
@@ -43,13 +43,15 @@ fn evaluate(
 
 #[magnus::init]
 fn init(ruby: &Ruby) -> Result<(), Error> {
-    let class = ruby.define_class("ExpressionParser", ruby.class_object())?;
+    let module = ruby.define_module("Lago")?;
+
+    let class = module.define_class("ExpressionParser", ruby.class_object())?;
     class.define_singleton_method("parse", function!(parse, 1))?;
 
-    let class = ruby.define_class("Expression", ruby.class_object())?;
+    let class = module.define_class("Expression", ruby.class_object())?;
     class.define_method("evaluate", method!(evaluate, 1))?;
 
-    let class = ruby.define_class("Event", ruby.class_object())?;
+    let class = module.define_class("Event", ruby.class_object())?;
     class.define_singleton_method("new", function!(EventWrapper::new, 3))?;
 
     Ok(())
diff --git a/expression-ruby/lago-expression.gemspec b/expression-ruby/lago-expression.gemspec
index 851c6d1..4a8d2e8 100644
--- a/expression-ruby/lago-expression.gemspec
+++ b/expression-ruby/lago-expression.gemspec
@@ -10,4 +10,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'libclang', '~> 14'
   spec.add_development_dependency 'rake-compiler', '~> 1.2'
   spec.add_development_dependency 'rb_sys', '~> 0.9'
+  spec.add_development_dependency 'rspec', '~> 3'
 end