diff --git a/app/controllers/weapps/attendances_controller.rb b/app/controllers/weapps/attendances_controller.rb
index dbba6e07c..a52e81173 100644
--- a/app/controllers/weapps/attendances_controller.rb
+++ b/app/controllers/weapps/attendances_controller.rb
@@ -10,7 +10,7 @@ class Weapps::AttendancesController < ApplicationController
     ActiveRecord::Base.transaction do
       attendance = @course.course_attendances.create!(create_params.merge(user_id: current_user.id))
       unless params[:group_ids].blank?
-        group_ids = @course.charge_group_ids(current_user) & params[:group_ids]
+        group_ids = @course.charge_group_ids(current_user) & params[:group_ids].map(&:to_i)
         group_ids.each do |group_id|
           @course.course_attendance_groups.create!(course_group_id: group_id, course_attendance: attendance)
         end