diff --git a/papers/commands/add_cmd.py b/papers/commands/add_cmd.py
index 57f4399..538c62e 100644
--- a/papers/commands/add_cmd.py
+++ b/papers/commands/add_cmd.py
@@ -39,7 +39,7 @@ def command(args):
         bibstr = ''
         while cont:
             try:
-                bibstr = files.editor_input(config, bibstr, suffix='.yaml')
+                bibstr = files.editor_input(config().edit_cmd, bibstr, suffix='.yaml')
                 key, bib = get_bibentry_from_string(bibstr)
                 cont = False
             except Exception:
diff --git a/papers/paper.py b/papers/paper.py
index a5885db..d1018f3 100644
--- a/papers/paper.py
+++ b/papers/paper.py
@@ -271,7 +271,10 @@ class Paper(object):
         self.tags.discard(tag)
 
 
-class PaperInRepo(Paper): # TODO document why this class exists (fabien, 2013/06)
+class PaperInRepo(Paper):
+    """Extend paper class with command specific to the case where the paper
+    lives in a repository.
+    """
 
     def __init__(self, repo, *args, **kwargs):
         Paper.__init__(self, *args, **kwargs)