diff --git a/Gemfile b/Gemfile
index cd18a6fa..30e18ca8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -19,7 +19,6 @@ end
 platforms :rbx do
   gem 'json'
   gem 'rubysl', '~> 2.0'
-  gem 'rubysl-test-unit', '~> 2.0' # Useful for Rails 3.2
   gem 'racc', '~> 1.4.10'
 end
 
diff --git a/Gemfile.edge b/Gemfile.edge
index b9812bb7..ae73399c 100644
--- a/Gemfile.edge
+++ b/Gemfile.edge
@@ -16,6 +16,7 @@ platforms :jruby do
 end
 
 platforms :rbx do
+  gem 'json'
   gem 'rubysl', '~> 2.0'
   gem 'racc', '~> 1.4.10'
 end
diff --git a/Gemfile.rails3 b/Gemfile.rails3
index b349e692..b8100898 100644
--- a/Gemfile.rails3
+++ b/Gemfile.rails3
@@ -18,7 +18,9 @@ platforms :jruby do
 end
 
 platforms :rbx do
+  gem 'json'
   gem 'rubysl', '~> 2.0'
+  gem 'rubysl-test-unit', '~> 2.0'
   gem 'racc', '~> 1.4.10'
 end