diff --git a/zerver/lib/bugdown/__init__.py b/zerver/lib/bugdown/__init__.py
index 911fe5a6ec..7e21ae3473 100644
--- a/zerver/lib/bugdown/__init__.py
+++ b/zerver/lib/bugdown/__init__.py
@@ -171,7 +171,7 @@ class InlineInterestingLinkProcessor(markdown.treeprocessors.Treeprocessor):
         match = re.match(youtube_re, url)
         if match is None:
             return None
-        return "http://i.ytimg.com/vi/%s/default.jpg" % (match.group(2),)
+        return "https://i.ytimg.com/vi/%s/default.jpg" % (match.group(2),)
 
     def twitter_link(self, url):
         tweet_id = get_tweet_id(url)
diff --git a/zerver/tests.py b/zerver/tests.py
index a64029f265..bc11987fce 100644
--- a/zerver/tests.py
+++ b/zerver/tests.py
@@ -2624,7 +2624,7 @@ xxxxxxx</strong></p>\n<p>xxxxxxx xxxxx xxxx xxxxx:<br>\n<code>xxxxxx</code>: xxx
         if settings.USING_EMBEDLY:
             self.assertEqual(converted, '<p>Check out the debate: <a href="http://www.youtube.com/watch?v=hx1mjT73xYE" target="_blank" title="http://www.youtube.com/watch?v=hx1mjT73xYE">http://www.youtube.com/watch?v=hx1mjT73xYE</a></p>\n<iframe width="250" height="141" src="http://www.youtube.com/embed/hx1mjT73xYE?feature=oembed" frameborder="0" allowfullscreen></iframe>')
         else:
-            self.assertEqual(converted, '<p>Check out the debate: <a href="http://www.youtube.com/watch?v=hx1mjT73xYE" target="_blank" title="http://www.youtube.com/watch?v=hx1mjT73xYE">http://www.youtube.com/watch?v=hx1mjT73xYE</a></p>\n<div class="message_inline_image"><a href="http://www.youtube.com/watch?v=hx1mjT73xYE" target="_blank" title="http://www.youtube.com/watch?v=hx1mjT73xYE"><img src="http://i.ytimg.com/vi/hx1mjT73xYE/default.jpg"></a></div>')
+            self.assertEqual(converted, '<p>Check out the debate: <a href="http://www.youtube.com/watch?v=hx1mjT73xYE" target="_blank" title="http://www.youtube.com/watch?v=hx1mjT73xYE">http://www.youtube.com/watch?v=hx1mjT73xYE</a></p>\n<div class="message_inline_image"><a href="http://www.youtube.com/watch?v=hx1mjT73xYE" target="_blank" title="http://www.youtube.com/watch?v=hx1mjT73xYE"><img src="https://i.ytimg.com/vi/hx1mjT73xYE/default.jpg"></a></div>')
 
     def test_inline_dropbox(self):
         msg = 'Look at how hilarious our old office was: https://www.dropbox.com/s/ymdijjcg67hv2ta/IMG_0923.JPG'