diff --git a/base.py b/base.py
index 75785bd..0d0fbca 100644
--- a/base.py
+++ b/base.py
@@ -123,7 +123,7 @@ class Config:
                 if 'instrument' in result:
                     raise ArgError('cannot give instrument twice')
                 result['instrument'] = arg
-            elif arg in argmap:
+            else:
                 kind = argmap.get(arg, other)
                 if kind is None:
                     raise ArgError(f'unexpected argument: {arg!r}')
diff --git a/frappy.py b/frappy.py
index b9e0dad..e344929 100644
--- a/frappy.py
+++ b/frappy.py
@@ -1,4 +1,5 @@
 import re
+import os
 from pathlib import Path
 from .base import MarcheControl, Logger, ArgError, write_content