diff --git a/app/controllers/notifications_controller.rb b/app/controllers/notifications_controller.rb
index e6c82e01ec6..1415f78f573 100644
--- a/app/controllers/notifications_controller.rb
+++ b/app/controllers/notifications_controller.rb
@@ -8,7 +8,7 @@ class NotificationsController < ApplicationController
     user =
       if params[:username] && !params[:recent]
         user_record = User.find_by(username: params[:username].to_s)
-        raise Discourse::InvalidParameters.new(:username) if !user_record
+        raise Discourse::NotFound if !user_record
         user_record
       else
         current_user
diff --git a/spec/controllers/notifications_controller_spec.rb b/spec/controllers/notifications_controller_spec.rb
index 99954375195..f521898bf07 100644
--- a/spec/controllers/notifications_controller_spec.rb
+++ b/spec/controllers/notifications_controller_spec.rb
@@ -36,8 +36,10 @@ describe NotificationsController do
 
       context 'when username params is not valid' do
         it 'should raise the right error' do
-          expect { xhr :get, :index, username: 'somedude' }
-            .to raise_error(Discourse::InvalidParameters)
+          xhr :get, :index, username: 'somedude'
+
+          expect(response).to_not be_success
+          expect(response.status).to eq(404)
         end
       end
     end