diff --git a/lib/spree/auth/engine.rb b/lib/spree/auth/engine.rb
index 01ed4480..185abe0f 100644
--- a/lib/spree/auth/engine.rb
+++ b/lib/spree/auth/engine.rb
@@ -14,7 +14,9 @@ class Engine < Rails::Engine
       end
 
       initializer "spree_auth_devise.set_user_class", after: :load_config_initializers do
-        Spree.user_class = 'Spree::User'
+        Rails.application.config.after_initialize do
+          Spree.user_class = 'Spree::User' if Spree.user_class.blank? || Spree.user_class.to_s == 'Spree::LegacyUser'
+        end
       end
 
       initializer "spree_auth_devise.check_secret_token" do