diff --git a/biostar/forum/markdown.py b/biostar/forum/markdown.py
index e91dca6c8..ba4b7d756 100644
--- a/biostar/forum/markdown.py
+++ b/biostar/forum/markdown.py
@@ -346,7 +346,7 @@ def embedder(attrs, new, embed=None):
         return attrs
 
     href = attrs['_text']
-    linkable = href[:4] in ('http', 'ftp:', 'https')
+    linkable = href.startswith(('http', 'ftp:', 'https'))
 
     # Don't linkify non http links
     if not linkable:
@@ -377,17 +377,14 @@ def embedder(attrs, new, embed=None):
 def linkify(text):
     # List of links to embed
     embed = []
-    html = bleach.linkify(text=text, callbacks=[partial(embedder, embed=embed)], skip_tags=['pre', 'code'])
+    html = bleach.linkify(text=text, callbacks=[partial(embedder, embed=embed), nofollow], skip_tags=['pre', 'code'])
 
     # Embed links into html.
     for em in embed:
         source, target = em
-        emb = f'<a href="{source}">{source}</a>'
+        emb = f'<a href="{source}" rel="nofollow">{source}</a>'
         html = html.replace(emb, target)
 
-    # Add nofollow to each link.
-    html = bleach.linkify(text=html, callbacks=[nofollow], skip_tags=['pre', 'code'])
-
     return html
 
 
diff --git a/biostar/forum/tests/test_markdown.py b/biostar/forum/tests/test_markdown.py
index 1e301f621..17d6dbc93 100644
--- a/biostar/forum/tests/test_markdown.py
+++ b/biostar/forum/tests/test_markdown.py
@@ -24,10 +24,10 @@
     (f"{settings.PROTOCOL}://{SITE_URL}/u/5 ", f'<p><a href="{settings.PROTOCOL}://{SITE_URL}/u/5" rel="nofollow">tested2</a></p>'),
 
     # Twitter link
-    ("https://twitter.com/Linux/status/2311234267", '<p></p><blockquote class="twitter-tweet"><p lang="en" dir="ltr">w00t! 10,000 followers!</p>— Linux (@Linux) <a href="https://twitter.com/Linux/status/2311234267?ref_src=twsrc%5Etfw" rel="nofollow">June 24, 2009</a></blockquote><script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script><p></p>'),
+    ("https://twitter.com/Linux/status/2311234267", '<p><blockquote class="twitter-tweet"><p lang="en" dir="ltr">w00t! 10,000 followers!</p>&mdash; Linux (@Linux) <a href="https://twitter.com/Linux/status/2311234267?ref_src=twsrc%5Etfw">June 24, 2009</a></blockquote><script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script></p>'),
 
     # Youtube link
-    ("https://www.youtube.com/watch?v=dQw4w9WgXcQ", '<p><iframe width="420" height="315" src="//www.youtube.com/embed/dQw4w9WgXcQ" frameborder="0" allowfullscreen=""></iframe></p>'),
+    ("https://www.youtube.com/watch?v=dQw4w9WgXcQ", '<p><iframe width="420" height="315" src="//www.youtube.com/embed/dQw4w9WgXcQ" frameborder="0" allowfullscreen></iframe></p>'),
 
     # Gist link
     ("https://gist.github.com/afrendeiro/6732a46b949e864d6803", '<p><script src="https://gist.github.com/afrendeiro/6732a46b949e864d6803.js"></script></p>'),