diff --git a/src/oidcmsg/logging.py b/src/oidcmsg/logging.py
index c628e07..537b151 100644
--- a/src/oidcmsg/logging.py
+++ b/src/oidcmsg/logging.py
@@ -38,7 +38,7 @@ def configure_logging(debug: Optional[bool] = False,
         config_source = 'dictionary'
     elif filename is not None and os.path.exists(filename):
         with open(filename, "rt") as file:
-            config_dict = yaml.load(file)
+            config_dict = yaml.safe_load(file)
         config_source = 'file'
     else:
         config_dict = LOGGING_DEFAULT
diff --git a/src/oidcmsg/time_util.py b/src/oidcmsg/time_util.py
index b8fc9dc..8991bd7 100644
--- a/src/oidcmsg/time_util.py
+++ b/src/oidcmsg/time_util.py
@@ -20,6 +20,7 @@
 """
 
 import calendar
+import logging
 import re
 import sys
 import time
@@ -30,6 +31,8 @@
 TIME_FORMAT_WITH_FRAGMENT = re.compile("^(\d{4,4}-\d{2,2}-\d{2,2}T\d{2,2}:\d{2,2}:\d{2,2})\.\d*Z$")
 
 
+logger = logging.getLogger(__name__)
+
 class TimeUtilError(Exception):
     pass
 
@@ -287,7 +290,7 @@ def str_to_time(timestr, time_format=TIME_FORMAT):
         try:
             elem = TIME_FORMAT_WITH_FRAGMENT.match(timestr)
         except Exception as exc:
-            print >>sys.stderr, "Exception: %s on %s" % (exc, timestr)
+            logger.error("Exception: %s on %s" % (exc, timestr))
             raise
         then = time.strptime(elem.groups()[0] + "Z", TIME_FORMAT)