diff --git a/app/models/post/image_uploader.rb b/app/models/post/image_uploader.rb
index ea16ad0..101b0fe 100644
--- a/app/models/post/image_uploader.rb
+++ b/app/models/post/image_uploader.rb
@@ -45,8 +45,9 @@ class Post::ImageUploader < CarrierWave::Uploader::Base
   # XXX los nombres de los archivos siempre son únicos, no chequeamos si
   # están repetidos.
   def filename
-    @unique_filename ||= if /\A[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\..*\Z/ =~ file.try(:filename)
-      file.try(:filename)
+    current_filename = parent_version.try(:filename) || file.try(:filename)
+    @unique_filename ||= if /\A(thumb_)?[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\..*\Z/ =~ current_filename
+      current_filename
     else
       [SecureRandom.uuid, '.', file.extension].join
     end