diff --git a/Gemfile b/Gemfile
index c66fc392..765bcee0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ gem "compass-validator", "3.0.1"
 gem "css_parser", "~> 1.0.1"
 gem "sass", "~>3.1"
 gem "haml", "~> 3.1"
-gem "rcov", :platform => :mri
+gem "rcov", :platform => :mri_18
 gem "rubyzip"
 gem "livereload"
 gem "ruby-prof", :platform => :mri