diff --git a/app/models/concerns/user.rb b/app/models/concerns/user.rb
index 28601cdf..89855062 100644
--- a/app/models/concerns/user.rb
+++ b/app/models/concerns/user.rb
@@ -26,6 +26,6 @@ module User
   end
 
   def to_s
-    name
+    displayname
   end
 end
diff --git a/app/models/external_user.rb b/app/models/external_user.rb
index 538f4997..8a7cbb58 100644
--- a/app/models/external_user.rb
+++ b/app/models/external_user.rb
@@ -5,8 +5,8 @@ class ExternalUser < ActiveRecord::Base
   validates :external_id, presence: true
 
   def displayname
-    result = name
-    if(consumer.name == 'openHPI')
+    result =  "User " + user_id
+    if(!consumer.nil? && consumer.name == 'openHPI')
       result = Rails.cache.fetch("#{cache_key}/displayname", expires_in: 12.hours) do
          Xikolo::UserClient.get(external_id.to_s)[:display_name]
       end