diff --git a/src/infrastructure/markup/rule/PhabricatorYoutubeRemarkupRule.php b/src/infrastructure/markup/rule/PhabricatorYoutubeRemarkupRule.php
--- a/src/infrastructure/markup/rule/PhabricatorYoutubeRemarkupRule.php
+++ b/src/infrastructure/markup/rule/PhabricatorYoutubeRemarkupRule.php
@@ -2,34 +2,37 @@
 
 final class PhabricatorYoutubeRemarkupRule extends PhutilRemarkupRule {
 
-  private $uri;
-
   public function getPriority() {
     return 350.0;
   }
 
   public function apply($text) {
-    $this->uri = new PhutilURI($text);
+    try {
+      $uri = new PhutilURI($text);
+    } catch (Exception $ex) {
+      return $text;
+    }
 
-    if ($this->uri->getDomain() &&
-        preg_match('/(^|\.)youtube\.com$/', $this->uri->getDomain()) &&
-        idx($this->uri->getQueryParams(), 'v')) {
-      return $this->markupYoutubeLink();
+    $domain = $uri->getDomain();
+    if (!preg_match('/(^|\.)youtube\.com\z/', $domain)) {
+      return $text;
     }
 
-    return $text;
-  }
+    $params = $uri->getQueryParams();
+    $v_param = idx($params, 'v');
+    if (!strlen($v_param)) {
+      return $text;
+    }
 
-  public function markupYoutubeLink() {
-    $v = idx($this->uri->getQueryParams(), 'v');
     $text_mode = $this->getEngine()->isTextMode();
     $mail_mode = $this->getEngine()->isHTMLMailMode();
 
     if ($text_mode || $mail_mode) {
-      return $this->getEngine()->storeText('http://youtu.be/'.$v);
+      return $text;
     }
 
-    $youtube_src = 'https://www.youtube.com/embed/'.$v;
+    $youtube_src = 'https://www.youtube.com/embed/'.$v_param;
+
     $iframe = $this->newTag(
       'div',
       array(
@@ -45,6 +48,7 @@
           'frameborder' => 0,
         ),
         ''));
+
     return $this->getEngine()->storeText($iframe);
   }