diff --git a/main.py b/main.py
index ae04670..60a2bda 100755
--- a/main.py
+++ b/main.py
@@ -39,12 +39,12 @@ class BaseConfig(dict):
     def _load(self):
         try:
             if self.file == '-':
-                config = yaml.load(sys.stdin, Loader=Loader)
+                config = yaml.safe_load(sys.stdin)
             else:
                 if os.stat(self.file).st_mode & 0o777 & ~0o600:
                     raise Exception('refusing to load insecure configuration file, file must have permission 0o600')
                 with open(self.file) as fp:
-                    config = yaml.load(fp, Loader=Loader)
+                    config = yaml.safe_load(fp)
             if config is None:
                 config = {}
             for k, v in config.items():
@@ -65,7 +65,7 @@ class BaseConfig(dict):
 
     def _save(self):
         with open(self.file, 'w') as fp:
-            yaml.dump(self, fp, Dumper=Dumper)
+            yaml.safe_dump(dict(self), fp)
 
     def exception(self):
         return self._ex
@@ -164,16 +164,23 @@ def init_logging():
 
 
 def set_logging_level(level: str):
-    allowed_values = {'NOTSET', 'DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'}
+    levels = {
+        'NOTSET': logging.NOTSET,
+        'DEBUG': logging.DEBUG,
+        'INFO': logging.INFO,
+        'WARNING': logging.WARNING,
+        'WARN': logging.WARNING,
+        'ERROR': logging.ERROR,
+        'CRITICAL': logging.CRITICAL,
+    }
 
     log_levels = [x.split(':') for x in level.split(',')]
     for module, level in log_levels:
         module = module.strip() if module else None
         level = level.strip().upper()
-        if level not in allowed_values:
-            raise ValueError(f'invalid log level, allowed values: {repr(allowed_values)}')
-        level = getattr(logging, level)
-        logging.getLogger(module).setLevel(level)
+        if level not in levels:
+            raise ValueError(f'invalid log level, allowed values: {repr(set(levels.keys()))}')
+        logging.getLogger(module).setLevel(levels[level])
 
 @click.command()
 @click.option('--config', '-c', envvar='WP_CAL_CONFIG', default='-', help='The configuration file')