diff --git a/activesupport/lib/active_support/core_ext/file/atomic.rb b/activesupport/lib/active_support/core_ext/file/atomic.rb
index 49d28e8a34..26b73ed442 100644
--- a/activesupport/lib/active_support/core_ext/file/atomic.rb
+++ b/activesupport/lib/active_support/core_ext/file/atomic.rb
@@ -14,6 +14,7 @@ class File
   #   end
   def self.atomic_write(file_name, temp_dir = Dir.tmpdir)
     require 'tempfile' unless defined?(Tempfile)
+    require 'fileutils' unless defined?(FileUtils)
 
     temp_file = Tempfile.new(basename(file_name), temp_dir)
     yield temp_file
@@ -31,7 +32,7 @@ class File
     end
 
     # Overwrite original file with temp file
-    rename(temp_file.path, file_name)
+    FileUtils.mv(temp_file.path, file_name)
 
     # Set correct permissions on new file
     chown(old_stat.uid, old_stat.gid, file_name)