diff --git a/offlineimap/repository/IMAP.py b/offlineimap/repository/IMAP.py
index 829741d..a04a4a4 100644
--- a/offlineimap/repository/IMAP.py
+++ b/offlineimap/repository/IMAP.py
@@ -544,7 +544,7 @@ class IMAPRepository(BaseRepository):
 
         :param foldername: Full path of the folder to be created."""
 
-        if foldername is '':
+        if foldername == '':
             return
 
         if self.getreference():