diff --git a/app/models/metadata_belongs_to.rb b/app/models/metadata_belongs_to.rb
index 8726f1b1..17ecaee8 100644
--- a/app/models/metadata_belongs_to.rb
+++ b/app/models/metadata_belongs_to.rb
@@ -50,10 +50,12 @@ class MetadataBelongsTo < MetadataRelatedPosts
     end
 
     # No duplicar las relaciones
-    if belongs_to[inverse].respond_to? :has_one
-      belongs_to[inverse].value = post.uuid.value
-    else
-      belongs_to[inverse].value = (belongs_to[inverse].value.dup << post.uuid.value) unless belongs_to.blank? || included?
+    if belongs_to.present?
+      if belongs_to[inverse].respond_to? :has_one
+        belongs_to[inverse].value = post.uuid.value
+      else
+        belongs_to[inverse].value = (belongs_to[inverse].value.dup << post.uuid.value) unless belongs_to.blank? || included?
+      end
     end
 
     true