diff --git a/app/helpers/icons_helper.rb b/app/helpers/icons_helper.rb
index 99006308e..9a39c0d47 100644
--- a/app/helpers/icons_helper.rb
+++ b/app/helpers/icons_helper.rb
@@ -46,6 +46,7 @@ module IconsHelper
   end
 
   def principal_icon(principal, **options)
+    return if principal.nil?
     raise ArgumentError, "First argument has to be a Principal, was #{principal.inspect}" unless principal.is_a?(Principal)
 
     principal_class = principal.class.name.downcase
diff --git a/test/helpers/icons_helper_test.rb b/test/helpers/icons_helper_test.rb
index ab0b58db4..3917480e5 100644
--- a/test/helpers/icons_helper_test.rb
+++ b/test/helpers/icons_helper_test.rb
@@ -107,6 +107,10 @@ class IconsHelperTest < Redmine::HelperTest
     assert_nil principal_icon(Principal.find(1))
   end
 
+  def test_principal_icon_should_not_raise_exception_for_nil
+    assert_nil principal_icon(nil)
+  end
+
   def test_activity_event_type_icon_should_return_correct_icon_for_reply_events
     expected = %r{<svg class="s18 icon-svg" aria-hidden="true"><use href="/assets/icons-\w+.svg#icon--comments"></use></svg>}
     assert_match expected, activity_event_type_icon('reply')