diff --git a/activesupport/lib/active_support/evented_file_update_checker.rb b/activesupport/lib/active_support/evented_file_update_checker.rb
index 6a02a838b720f6c0619e8d679074c930bbb142b0..21fdf7bb807177e6c2da723e373d4a39a1742dca 100644
--- a/activesupport/lib/active_support/evented_file_update_checker.rb
+++ b/activesupport/lib/active_support/evented_file_update_checker.rb
@@ -86,16 +86,6 @@ def directories_to_watch
       end
 
     class PathHelper
-      using Module.new {
-        refine Pathname do
-          def ascendant_of?(other)
-            self != other && other.ascend do |ascendant|
-              break true if self == ascendant
-            end
-          end
-        end
-      }
-
       def xpath(path)
         Pathname.new(path).expand_path
       end
@@ -112,7 +102,7 @@ def longest_common_subpath(paths)
         lcsp = Pathname.new(paths[0])
 
         paths[1..-1].each do |path|
-          until lcsp.ascendant_of?(path)
+          until ascendant_of?(lcsp, path)
             if lcsp.root?
               # If we get here a root directory is not an ascendant of path.
               # This may happen if there are paths in different drives on
@@ -145,13 +135,21 @@ def filter_out_descendants(dirs)
           dir = dirs_sorted_by_nparts.shift
 
           dirs_sorted_by_nparts.reject! do |possible_descendant|
-            dir.ascendant_of?(possible_descendant) && descendants << possible_descendant
+            ascendant_of?(dir, possible_descendant) && descendants << possible_descendant
           end
         end
 
         # Array#- preserves order.
         dirs - descendants
       end
+
+      private
+
+        def ascendant_of?(base, other)
+          base != other && other.ascend do |ascendant|
+            break true if base == ascendant
+          end
+        end
     end
   end
 end