diff --git a/Rakefile b/Rakefile
index 23e1d0f..2201452 100644
--- a/Rakefile
+++ b/Rakefile
@@ -24,6 +24,8 @@ CLEAN.include(
   'lib/oga/xml/parser.rb',
   'lib/oga/xpath/lexer.rb',
   'lib/oga/xpath/parser.rb',
+  'lib/oga/css/lexer.rb',
+  'lib/oga/css/parser.rb',
   'benchmark/fixtures/big.xml',
   'profile/samples/**/*.txt',
   'lib/liboga.*',