diff --git a/server.py b/server.py
index 1e5559fffe03ce18a3cd929f3f4b193a9a89d991..ba75c7e4f5a7fa21e703720726f02ed7037a0793 100644
--- a/server.py
+++ b/server.py
@@ -25,14 +25,14 @@ def validate():
     xml_str = request.data
     xml_tree = utils.parse(xml_str)
     if xml_tree:
-        print('=== xml_tree OK ===')
+        app.logger.debug('=== xml_tree OK ===')
         xsd_str = utils.get_xsd(config, xsd_version=xv, xml_str=xml_str)
         if  xsd_str:
             ret = utils.validate(xml_str=xml_str, xsd_str=xsd_str)
         else:
             ret = utils.return_error(error='xsd content not readable')
     else: 
-        print('=== xml_tree ??? ===') 
+        app.logger.debug('=== xml_tree invalid ===') 
         ret = utils.return_error(error='invalid xml data')
 
     return  utils.xml_response(ret)