diff --git a/mopidy/commands.py b/mopidy/commands.py
index 72888e05..022419a8 100644
--- a/mopidy/commands.py
+++ b/mopidy/commands.py
@@ -100,7 +100,7 @@ class Command(object):
         self._children[name] = command
 
     def add_argument(self, *args, **kwargs):
-        """Add am argument to the parser.
+        """Add an argument to the parser.
 
         This method takes all the same arguments as the
         :class:`argparse.ArgumentParser` version of this method.