diff --git a/mopidy_subidy/subsonic_api.py b/mopidy_subidy/subsonic_api.py
index 86ef566..74afc97 100644
--- a/mopidy_subidy/subsonic_api.py
+++ b/mopidy_subidy/subsonic_api.py
@@ -18,6 +18,14 @@ ref_sort_key = lambda ref: ref.name
 
 string_nums_nocase_sort_key = lambda s: [(int(i) if i.isdigit() else i.lower()) for i in re.split(r'(\d+)', s)]
 
+def diritem_sort_key(item):
+    isdir = item['isDir']
+    if isdir:
+        key = string_nums_nocase_sort_key(item['title'])
+    else:
+        key = int(item['track'])
+    return (isdir, key)
+
 class SubsonicApi():
     def __init__(self, url, username, password, legacy_auth):
         parsed = urlparse(url)
@@ -162,8 +170,7 @@ class SubsonicApi():
         directory = response.get('directory')
         if directory is not None:
             diritems = directory.get('child')
-            sorted_diritems = sorted(diritems, key=lambda a: (a['isDir'], (string_nums_nocase_sort_key(a['title']) if a['isDir'] else int(a['track']))))
-            return sorted_diritems
+            return sorted(diritems, key=diritem_sort_key)
         return None
 
     def get_raw_albums(self, artist_id):