diff --git a/plugins/category_generator.rb b/plugins/category_generator.rb
index a40600f..d9357bc 100644
--- a/plugins/category_generator.rb
+++ b/plugins/category_generator.rb
@@ -70,7 +70,7 @@ module Jekyll
       if self.layouts.key? 'category_index'
         dir = self.config['category_dir'] || 'categories'
         self.categories.keys.each do |category|
-          self.write_category_index(File.join(dir, category.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-')), category)
+          self.write_category_index(File.join(dir, category.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-').downcase), category)
         end
 
       # Throw an exception if the layout couldn't be found.
@@ -107,7 +107,7 @@ module Jekyll
     def category_links(categories)
       dir = @context.registers[:site].config['category_dir']
       categories = categories.sort!.map do |item|
-        "<a class='category' href='/#{dir}/#{item.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-')}/'>#{item}</a>"
+        "<a class='category' href='/#{dir}/#{item.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-').downcase}/'>#{item}</a>"
       end
 
       case categories.length