diff --git a/lib/jekyll/cleaner.rb b/lib/jekyll/cleaner.rb
index fee6418a..cbcedcec 100644
--- a/lib/jekyll/cleaner.rb
+++ b/lib/jekyll/cleaner.rb
@@ -24,7 +24,9 @@ module Jekyll
     #
     # Returns an Array of the file and directory paths
     def obsolete_files
-      (existing_files - new_files - new_dirs + replaced_files).to_a
+      out = (existing_files - new_files - new_dirs + replaced_files).to_a
+      Jekyll::Hooks.trigger :clean, :on_obsolete, out
+      out
     end
 
     # Private: The metadata file storing dependency tree and build history
diff --git a/lib/jekyll/hooks.rb b/lib/jekyll/hooks.rb
index 8007edff..64496b53 100644
--- a/lib/jekyll/hooks.rb
+++ b/lib/jekyll/hooks.rb
@@ -39,6 +39,9 @@ module Jekyll
         :post_render => [],
         :post_write  => [],
       },
+      :clean     => {
+        :on_obsolete => [],
+      },
     }
 
     # map of all hooks and their priorities