diff --git a/middleman-core/lib/middleman-core/application.rb b/middleman-core/lib/middleman-core/application.rb
index 9a19ba93..8c2c9352 100644
--- a/middleman-core/lib/middleman-core/application.rb
+++ b/middleman-core/lib/middleman-core/application.rb
@@ -142,10 +142,6 @@ module Middleman
     # Setup custom rendering
     include Middleman::CoreExtensions::Rendering
 
-    # Parse YAML from templates. Must be before sitemap so sitemap
-    # extensions see updated frontmatter!
-    register Middleman::CoreExtensions::FrontMatter
-
     # Sitemap Config options and public api
     include Middleman::Sitemap
 
@@ -182,6 +178,10 @@ module Middleman
       # Setup the default values from calls to set before initialization
       self.class.config.load_settings(self.class.superclass.config.all_settings)
 
+      # Parse YAML from templates. Must be before sitemap so sitemap
+      # extensions see updated frontmatter!
+      activate :front_matter
+
       # Initialize the Sitemap
       @sitemap = ::Middleman::Sitemap::Store.new(self)
 
diff --git a/middleman-core/lib/middleman-core/core_extensions.rb b/middleman-core/lib/middleman-core/core_extensions.rb
index d61e90a7..340ca2fd 100644
--- a/middleman-core/lib/middleman-core/core_extensions.rb
+++ b/middleman-core/lib/middleman-core/core_extensions.rb
@@ -12,7 +12,10 @@ require 'middleman-core/core_extensions/extensions'
 require 'middleman-core/core_extensions/data'
 
 # Parse YAML from templates
-require 'middleman-core/core_extensions/front_matter'
+Middleman::Extensions.register :front_matter do
+  require 'middleman-core/core_extensions/front_matter'
+  Middleman::CoreExtensions::FrontMatter
+end
 
 # External helpers looks in the helpers/ folder for helper modules
 require 'middleman-core/core_extensions/external_helpers'
diff --git a/middleman-core/lib/middleman-core/core_extensions/extensions.rb b/middleman-core/lib/middleman-core/core_extensions/extensions.rb
index da366272..cdb0ed87 100644
--- a/middleman-core/lib/middleman-core/core_extensions/extensions.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/extensions.rb
@@ -62,19 +62,6 @@ module Middleman
         def configure(env, &block)
           send("#{env}_config", &block)
         end
-
-        # Register a new extension
-        #
-        # @param [Module] extension Extension modules to register
-        # @param [Hash] options Per-extension options hash
-        # @return [void]
-        def register(extension, options={}, &block)
-          if extension.ancestors.include?(::Middleman::Extension)
-            extension.new(self, options, &block)
-          else
-            $stderr.puts "!! Tried to register old-style extension: #{extension}"
-          end
-        end
       end
 
       # Instance methods
diff --git a/middleman-core/lib/middleman-core/sitemap.rb b/middleman-core/lib/middleman-core/sitemap.rb
index fbda5b2d..658dc7c5 100644
--- a/middleman-core/lib/middleman-core/sitemap.rb
+++ b/middleman-core/lib/middleman-core/sitemap.rb
@@ -1,6 +1,5 @@
 # Core Sitemap Extensions
 module Middleman
-
   module Sitemap
 
     # Setup Extension