diff --git a/README.md b/README.md
index e1490f1..0c1901d 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ If the tool works for you, please take a moment to __add your phone/OS to__ [the
   + Automatic: `./android-interact.sh db`. It may use an incorrect userid.
   + Manual:
     + Figure out your `${userid}` by inspecting the contents of `/data/data/com.tencent.mm/MicroMsg` on the __root__ filesystem of the device. It should be a 32-character-long name consisting of hexadecimal digits.
-    + Get `/data/data/com.tencent.mm/MicroMsg/${userid}/{EnMicroMsg.db,sfs/avatar.index}` from the device.
+    + Get `/data/data/com.tencent.mm/MicroMsg/${userid}/EnMicroMsg.db` from the device.
 2. Decrypt database file:
   + Automatic: `./decrypt-db.py decrypt --input EnMicroMsg.db`
   + Manual:
diff --git a/dump-html.py b/dump-html.py
index 80088e8..02825a2 100755
--- a/dump-html.py
+++ b/dump-html.py
@@ -17,7 +17,7 @@ def get_args():
     parser.add_argument('name', help='name of contact')
     parser.add_argument('--output', help='output html file', default='output.html')
     parser.add_argument('--db', default='decrypted.db', help='path to decrypted database')
-    parser.add_argument('--avt', default='avatar.index', help='path to avatar.index file')
+    parser.add_argument('--avt', default='avatar.index', help='path to avatar.index file that only exists in old version of wechat')
     parser.add_argument('--res', default='resource', help='reseource directory')
     args = parser.parse_args()
     return args
diff --git a/wechat/res.py b/wechat/res.py
index d70c486..6c2fc12 100644
--- a/wechat/res.py
+++ b/wechat/res.py
@@ -30,6 +30,11 @@ JPEG_QUALITY = 50
 class Resource(object):
     """ multimedia resources in chat"""
     def __init__(self, parser, res_dir, avt_db):
+        """
+        Args:
+            res_dir: path to the resource directory
+            avt_db: "avatar.index" file that only exists in old versions of wechat
+        """
         def check(subdir):
             dir_to_check = os.path.join(res_dir, subdir)
             assert os.path.isdir(dir_to_check), f"No such directory: {dir_to_check}"