diff --git a/extensions/mentions/src/Formatter/UnparsePostMentions.php b/extensions/mentions/src/Formatter/UnparsePostMentions.php
index f223dd638f..78a692bfd5 100644
--- a/extensions/mentions/src/Formatter/UnparsePostMentions.php
+++ b/extensions/mentions/src/Formatter/UnparsePostMentions.php
@@ -30,9 +30,9 @@ public function __construct(TranslatorInterface $translator)
      *
      * @param string $xml
      * @param mixed $context
-     * @return string $xml to be unparsed
+     * @return mixed $xml to be unparsed
      */
-    public function __invoke($context, string $xml)
+    public function __invoke($context, $xml)
     {
         $xml = $this->updatePostMentionTags($context, $xml);
         $xml = $this->unparsePostMentionTags($xml);
diff --git a/extensions/mentions/src/Formatter/UnparseTagMentions.php b/extensions/mentions/src/Formatter/UnparseTagMentions.php
index b2cae82f2f..a0075cb310 100644
--- a/extensions/mentions/src/Formatter/UnparseTagMentions.php
+++ b/extensions/mentions/src/Formatter/UnparseTagMentions.php
@@ -20,9 +20,9 @@ class UnparseTagMentions
      *
      * @param string $xml
      * @param mixed $context
-     * @return string $xml to be unparsed
+     * @return mixed $xml to be unparsed
      */
-    public function __invoke($context, string $xml)
+    public function __invoke($context, $xml)
     {
         $xml = $this->updateTagMentionTags($context, $xml);
         $xml = $this->unparseTagMentionTags($xml);
diff --git a/extensions/mentions/src/Formatter/UnparseUserMentions.php b/extensions/mentions/src/Formatter/UnparseUserMentions.php
index b150d2f7ba..6ca5bb3dfd 100644
--- a/extensions/mentions/src/Formatter/UnparseUserMentions.php
+++ b/extensions/mentions/src/Formatter/UnparseUserMentions.php
@@ -31,9 +31,9 @@ public function __construct(TranslatorInterface $translator)
      *
      * @param string $xml
      * @param mixed $context
-     * @return string $xml to be unparsed
+     * @return mixed $xml to be unparsed
      */
-    public function __invoke($context, string $xml)
+    public function __invoke($context, $xml)
     {
         $xml = $this->updateUserMentionTags($context, $xml);
         $xml = $this->unparseUserMentionTags($xml);