diff --git a/app/mailers/group_membership_mailer.rb b/app/mailers/group_membership_mailer.rb
index e7b6964b2..a395f4c4f 100644
--- a/app/mailers/group_membership_mailer.rb
+++ b/app/mailers/group_membership_mailer.rb
@@ -35,6 +35,6 @@ def placeholder_group_link
     group_links = @group.with_layer.map do |g|
       link_to(g, group_url(g))
     end
-    group_links.join(" / ")
+    join_lines(group_links, " / ")
   end
 end