diff --git a/modules/config.py b/modules/config.py
index 97638a93..5b76f376 100644
--- a/modules/config.py
+++ b/modules/config.py
@@ -7,7 +7,8 @@ import enum
 from src import ModuleManager, utils
 
 class ConfigInvalidValue(Exception):
-    pass
+    def __init__(self, message: str=None):
+        self.message = message
 class ConfigSettingInexistent(Exception):
     pass
 
@@ -113,7 +114,11 @@ class Module(ModuleManager.BaseModule):
 
     def _config(self, export_settings, target, setting, value=None):
         if not value == None:
-            validated_value = export_settings[setting].parse(value)
+            try:
+                validated_value = export_settings[setting].parse(value)
+            except utils.SettingParseException as e:
+                raise ConfigInvalidValue(str(e))
+
             if not validated_value == None:
                 target.set_setting(setting, validated_value)
                 return ConfigResult(ConfigResults.Changed, validated_value)
@@ -199,7 +204,10 @@ class Module(ModuleManager.BaseModule):
 
             try:
                 result = self._config(export_settings, target, setting, value)
-            except ConfigInvalidValue:
+            except ConfigInvalidValue as e:
+                if not e.message == None:
+                    raise utils.EventError("Invalid value: %s" % e.message)
+
                 example = export_settings[setting].get_example()
                 if not example == None:
                     raise utils.EventError("Invalid value. %s" %
diff --git a/modules/ircv3_sasl/__init__.py b/modules/ircv3_sasl/__init__.py
index 5eb704f7..40f5afc0 100644
--- a/modules/ircv3_sasl/__init__.py
+++ b/modules/ircv3_sasl/__init__.py
@@ -12,10 +12,17 @@ USERPASS_MECHANISMS = [
     "SCRAM-SHA-1",
     "PLAIN"
 ]
+ALL_MECHANISMS = USERPASS_MECHANISMS+["EXTERNAL"]
 
 def _parse(value):
     mechanism, _, arguments = value.partition(" ")
-    return {"mechanism": mechanism.upper(), "args": arguments}
+    mechanism = mechanism.upper()
+
+    if mechanism in ALL_MECHANISMS:
+        return {"mechanism": mechanism.upper(), "args": arguments}
+    else:
+        raise utils.SettingParseException("Unknown SASL mechanism '%s'"
+            % mechanism)
 
 HARDFAIL = utils.BoolSetting("sasl-hard-fail",
     "Set whether a SASL failure should cause a disconnect")
diff --git a/src/utils/__init__.py b/src/utils/__init__.py
index 36157204..e9e7bee5 100644
--- a/src/utils/__init__.py
+++ b/src/utils/__init__.py
@@ -264,6 +264,9 @@ def is_ip(s: str) -> bool:
 def is_main_thread() -> bool:
     return threading.current_thread() is threading.main_thread()
 
+class SettingParseException(Exception):
+    pass
+
 class Setting(object):
     example: typing.Optional[str] = None
     def __init__(self, name: str, help: str=None, example: str=None):