diff --git a/lib/jekyll/configuration.rb b/lib/jekyll/configuration.rb
index d6856bb1..50dca537 100644
--- a/lib/jekyll/configuration.rb
+++ b/lib/jekyll/configuration.rb
@@ -164,6 +164,15 @@ module Jekyll
         config.delete('server')
       end
 
+      if config.has_key? 'server_port'
+        Jekyll::Logger.warn "Deprecation:", "The 'server_port' configuration option" +
+                            " has been renamed to 'port'. Please update your config" +
+                            " file accordingly."
+        # copy but don't overwrite:
+        config['port'] = config['server_port'] unless config.has_key?('port')
+        config.delete('server_port')
+      end
+
       config
     end