diff --git a/app/controllers/subjects_controller.rb b/app/controllers/subjects_controller.rb
index a62707536..dad2636ea 100644
--- a/app/controllers/subjects_controller.rb
+++ b/app/controllers/subjects_controller.rb
@@ -269,7 +269,7 @@ class SubjectsController < ApplicationController
     page = params[:page] || 1
     member_ids = @subject.subject_members.map(&:user_id).join(',')
     condition = "%#{params[:search].strip}%".gsub(" ","")
-    @users = User.where("id not in (?) and status = 1 and LOWER(concat(lastname, firstname, login, mail)) LIKE ?", member_ids, "#{condition}")
+    @users = User.where("id not in (?) and status = 1 and LOWER(concat(lastname, ifnull(firstname, ''), login)) LIKE ?", member_ids, "#{condition}")
 
     @users = @users.page(page).per(10)
     @users = @users.includes(:user_extension)