diff --git a/app/models/metadata_belongs_to.rb b/app/models/metadata_belongs_to.rb
index 0626ba0..ee182a5 100644
--- a/app/models/metadata_belongs_to.rb
+++ b/app/models/metadata_belongs_to.rb
@@ -3,13 +3,6 @@
 # Almacena el UUID de otro Post y actualiza el valor en el Post
 # relacionado.
 class MetadataBelongsTo < MetadataRelatedPosts
-  def value_was=(new_value)
-    @belongs_to = nil
-    @belonged_to = nil
-
-    super(new_value)
-  end
-
   # TODO: Convertir algunos tipos de valores en módulos para poder
   # implementar varios tipos de campo sin repetir código
   #
@@ -39,10 +32,14 @@ class MetadataBelongsTo < MetadataRelatedPosts
 
     # Si estamos cambiando la relación, tenemos que eliminar la relación
     # anterior
-    belonged_to[inverse].value.delete post.uuid.value if changed? && belonged_to.present?
+    if belonged_to.present?
+      belonged_to[inverse].value = belonged_to[inverse].value.reject do |rej|
+        rej == post.uuid.value
+      end
+    end
 
     # No duplicar las relaciones
-    belongs_to[inverse].value << post.uuid.value unless belongs_to.blank? || included?
+    belongs_to[inverse].value = (belongs_to[inverse].value.dup << post.uuid.value) unless belongs_to.blank? || included?
 
     true
   end
@@ -63,20 +60,13 @@ class MetadataBelongsTo < MetadataRelatedPosts
   end
 
   # El Post relacionado con este artículo
-  #
-  # XXX: Memoizamos usando el valor para tener el valor siempre
-  # actualizado.
   def belongs_to
-    return if value.blank?
-
-    @belongs_to ||= posts.find(value, uuid: true)
+    posts.find(value, uuid: true) if value.present?
   end
 
   # El artículo relacionado anterior
   def belonged_to
-    return if value_was.blank?
-
-    @belonged_to ||= posts.find(value_was, uuid: true)
+    posts.find(value_was, uuid: true) if value_was.present?
   end
 
   def related_posts?
diff --git a/test/models/metadata_belongs_to_test.rb b/test/models/metadata_belongs_to_test.rb
new file mode 100644
index 0000000..bf3f7b6
--- /dev/null
+++ b/test/models/metadata_belongs_to_test.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+require_relative 'metadata_test'
+
+class MetadataBelongsToTest < ActiveSupport::TestCase
+  include MetadataTest
+
+  test 'se pueden relacionar artículos' do
+    post = @site.posts.create(layout: :post, title: SecureRandom.hex)
+    reply = @site.posts.create(layout: :post, title: SecureRandom.hex, in_reply_to: post.uuid.value)
+
+    assert_equal post, reply.in_reply_to.belongs_to
+    assert_includes post.posts.has_many, reply
+  end
+
+  test 'se puede eliminar la relación' do
+    post = @site.posts.create(layout: :post, title: SecureRandom.hex)
+    reply = @site.posts.create(layout: :post, title: SecureRandom.hex, in_reply_to: post.uuid.value)
+
+    reply.in_reply_to.value = ''
+    reply.save
+
+    assert_not_equal post, reply.in_reply_to.belongs_to
+    assert_equal post, reply.in_reply_to.belonged_to
+    assert_nil reply.in_reply_to.belongs_to
+    assert_not_includes post.posts.has_many, reply
+  end
+
+  test 'se puede cambiar la relación' do
+    post1 = @site.posts.create(layout: :post, title: SecureRandom.hex)
+    post2 = @site.posts.create(layout: :post, title: SecureRandom.hex)
+    reply = @site.posts.create(layout: :post, title: SecureRandom.hex, in_reply_to: post1.uuid.value)
+
+    reply.in_reply_to.value = post2.uuid.value
+    reply.save
+
+    assert_not_equal post1, reply.in_reply_to.belongs_to
+    assert_equal post1, reply.in_reply_to.belonged_to
+    assert_not_includes post1.posts.has_many, reply
+
+    assert_equal post2, reply.in_reply_to.belongs_to
+    assert_includes post2.posts.has_many, reply
+  end
+end