diff --git a/_plugins/categories.rb b/_plugins/categories.rb
index 69e437a..9f5eaaf 100644
--- a/_plugins/categories.rb
+++ b/_plugins/categories.rb
@@ -1,6 +1,5 @@
 module Jekyll
   module Filters
-
     # Outputs a list of categories as comma-separated <a> links. This is used
     # to output the category list for each post on a category page.
     #
@@ -9,7 +8,7 @@ module Jekyll
     # Returns string
     #
     def category_list(categories)
-      categories.sort.join(', ')
+      categories.sort.join(", ")
     end
   end
 end