diff --git a/app/helpers/avatars_helper.rb b/app/helpers/avatars_helper.rb
index 88a571b62..cd9c1d66e 100644
--- a/app/helpers/avatars_helper.rb
+++ b/app/helpers/avatars_helper.rb
@@ -44,7 +44,7 @@ module AvatarsHelper
       if user.respond_to?(:mail)
         email = user.mail
         options[:title] = user.name unless options[:title]
-        options[:initials] = user.initials if options[:default] == "initials"
+        options[:initials] = user.initials if options[:default] == "initials" && user.initials.present?
       elsif user.to_s =~ %r{<(.+?)>}
         email = $1
       end
diff --git a/app/models/principal.rb b/app/models/principal.rb
index 86c4edb84..0a6c32ba2 100644
--- a/app/models/principal.rb
+++ b/app/models/principal.rb
@@ -130,6 +130,11 @@ class Principal < ApplicationRecord
     to_s
   end
 
+  # Returns nil by default, subclasses should implement this method
+  def initials(formatter = nil)
+    nil
+  end
+
   def mail=(*args)
     nil
   end
diff --git a/test/unit/principal_test.rb b/test/unit/principal_test.rb
index 9eef5bbf3..61f775014 100644
--- a/test/unit/principal_test.rb
+++ b/test/unit/principal_test.rb
@@ -166,4 +166,8 @@ class PrincipalTest < ActiveSupport::TestCase
     r = Principal.like('vi_ci')
     assert_include user, r
   end
+
+  def test_initials_should_return_nil
+    assert_nil Group.first.initials
+  end
 end