diff --git a/app/services/api/v1/projects/contributors/stat_service.rb b/app/services/api/v1/projects/contributors/stat_service.rb
index d4560be5d..ab20dd657 100644
--- a/app/services/api/v1/projects/contributors/stat_service.rb
+++ b/app/services/api/v1/projects/contributors/stat_service.rb
@@ -26,7 +26,7 @@ class Api::V1::Projects::Contributors::StatService < ApplicationService
       access_token: token, page: page, limit: limit
     }
     param.merge!(branch: branch) if branch.present?
-    param.merge!(pass_year: pass_year) if pass_year.present?
+    param.merge!(pass_year: @pass_year)
 
     param
   end