diff --git a/qutebrowser/commands/argparser.py b/qutebrowser/commands/argparser.py
index 30299128b..2e8e18f0b 100644
--- a/qutebrowser/commands/argparser.py
+++ b/qutebrowser/commands/argparser.py
@@ -81,7 +81,7 @@ class ArgumentParser(argparse.ArgumentParser):
         raise ArgumentParserExit(status, msg)
 
     def error(self, msg):
-        raise ArgumentParserError(msg[0].upper() + msg[1:])
+        raise ArgumentParserError(msg.capitalize())
 
 
 def enum_getter(enum):
@@ -101,11 +101,11 @@ def enum_getter(enum):
     return _get_enum_item
 
 
-def multitype_conv(tpl):
+def multitype_conv(types):
     """Function factory to get a type converter for a choice of types."""
     def _convert(value):
         """Convert a value according to an iterable of possible arg types."""
-        for typ in set(tpl):
+        for typ in set(types):
             if isinstance(typ, str):
                 if value == typ:
                     return value