diff --git a/app/models/post.rb b/app/models/post.rb
index 3a1dcd12..0a7b9596 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -113,7 +113,7 @@ class Post < OpenStruct
 
       # Notificar a les usuaries que están viendo una previsualización
       # XXX: Asume que estamos usando Bootstrap :B
-      html.at_css('body').first_element_child.before("<div class=\"alert alert-warning text-center\">#{I18n.t('posts.preview.message')}</div>")
+      html.at_css('body')&.first_element_child&.before("<div class=\"alert alert-warning text-center\">#{I18n.t('posts.preview.message')}</div>")
 
       # Cacofonía
       html.to_html.html_safe