diff --git a/lib/rdoc/markup/simple_markup/to_flow.rb b/lib/rdoc/markup/simple_markup/to_flow.rb
index ce366d2df7..4718cfaaf6 100644
--- a/lib/rdoc/markup/simple_markup/to_flow.rb
+++ b/lib/rdoc/markup/simple_markup/to_flow.rb
@@ -1,6 +1,6 @@
 require 'rdoc/markup/simple_markup/fragments'
 require 'rdoc/markup/simple_markup/inline'
-require 'CGI'
+require 'cgi'
 
 module SM