diff --git a/telethon/extensions/markdown.py b/telethon/extensions/markdown.py
index cab1d6a1..be0ea507 100644
--- a/telethon/extensions/markdown.py
+++ b/telethon/extensions/markdown.py
@@ -161,13 +161,17 @@ def unparse(text, entities, delimiters=None, url_fmt=None):
         delimiter = delimiters.get(type(entity), None)
         if delimiter:
             text = text[:s] + delimiter + text[s:e] + delimiter + text[e:]
-        elif isinstance(entity, MessageEntityTextUrl) and url_fmt:
-            text = (
-                text[:s] +
-                add_surrogate(url_fmt.format(text[s:e], entity.url)) +
-                text[e:]
-            )
-        elif isinstance(entity, MessageEntityMentionName):
-            text = text[:s] + "[{}](tg://user?id={})".format(
-                text[s:e], entity.user_id) + text[e:]
+        elif url_fmt:
+            url = None
+            if isinstance(entity, MessageEntityTextUrl):
+                url = entity.url
+            elif isinstance(entity, MessageEntityMentionName):
+                url = 'tg://user?id={}'.format(entity.user_id)
+            if url:
+                text = (
+                    text[:s] +
+                    add_surrogate(url_fmt.format(text[s:e], url)) +
+                    text[e:]
+                )
+
     return del_surrogate(text)