diff --git a/pymcuprog/serialupdi/physical.py b/pymcuprog/serialupdi/physical.py
index 1ac0e4b..557905f 100644
--- a/pymcuprog/serialupdi/physical.py
+++ b/pymcuprog/serialupdi/physical.py
@@ -49,7 +49,7 @@ def _loginfo(self, msg, data):
             i_data = [ord(x) for x in data]
         else:
             i_data = data
-        data_str = "[" + ", ".join([hex(x) for x in i_data]) + "]"
+        data_str = "[" + ", ".join(["0x{:02X}".format(x) for x in i_data]) + "]"
         self.logger.debug("%s : %s", msg, data_str)
 
     def send_double_break(self):