diff --git a/spec/factories/groups.rb b/spec/factories/groups.rb
index 841f741..748cb69 100644
--- a/spec/factories/groups.rb
+++ b/spec/factories/groups.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :group do
-    number { 0 }
+    sequence(:number)
     stage
   end
 end