diff --git a/app/api/mobile/apis/memos.rb b/app/api/mobile/apis/memos.rb
index 4e8f4f97..89412316 100644
--- a/app/api/mobile/apis/memos.rb
+++ b/app/api/mobile/apis/memos.rb
@@ -34,7 +34,7 @@ module Mobile
             Rails.logger.info("####11111222##{@env['HTTP_X_REAL_IP']}")
             ip = @env['HTTP_X_REAL_IP']
             ua = UserAgent.where(:ip => ip)
-            unless ua
+            if ua.blank?
               UserAgent.create!(:key => params[:edu].strip, :ip => ip, :type => UserAgent::AD)
             end
           end