diff --git a/lib/jekyll/commands/serve.rb b/lib/jekyll/commands/serve.rb
index 6467c5ab..912f4f62 100644
--- a/lib/jekyll/commands/serve.rb
+++ b/lib/jekyll/commands/serve.rb
@@ -40,7 +40,7 @@ module Jekyll
 
           s.mount(
             options['baseurl'],
-            WEBrick::HTTPServlet::FileHandler,
+            FileHandler,
             destination,
             file_handler_options
           )
@@ -131,6 +131,19 @@ module Jekyll
 
       end
 
+      # Custom WEBrick FileHandler servlet for serving "/file.html" at "/file"
+      # when no exact match is found. This mirrors the behavior of GitHub Pages
+      # and many static web server configs.
+      require 'webrick'
+      class FileHandler < ::WEBrick::HTTPServlet::FileHandler
+        def search_file(req, res, basename)
+          if file = super
+            file
+          else
+            super(req, res, "#{basename}.html")
+          end
+        end
+      end
     end
   end
 end