diff --git a/phpBB/includes/functions_posting.php b/phpBB/includes/functions_posting.php
index 23fdd809e2..f9be0f10f6 100644
--- a/phpBB/includes/functions_posting.php
+++ b/phpBB/includes/functions_posting.php
@@ -398,11 +398,12 @@ function posting_gen_topic_types($forum_id, $cur_topic_type = POST_NORMAL)
 * @param string			$local_storage	The path to the local file
 * @param bool			$is_message		Whether it is a PM or not
 * @param \filespec		$local_filedata	A filespec object created for the local file
+* @param \phpbb\mimetype\guesser	$mimetype_guesser	The mimetype guesser object if used
 * @param \phpbb\plupload\plupload	$plupload		The plupload object if one is being used
 *
 * @return object filespec
 */
-function upload_attachment($form_name, $forum_id, $local = false, $local_storage = '', $is_message = false, $local_filedata = false, \phpbb\plupload\plupload $plupload = null)
+function upload_attachment($form_name, $forum_id, $local = false, $local_storage = '', $is_message = false, $local_filedata = false, \phpbb\mimetype\guesser $mimetype_guesser = null, \phpbb\plupload\plupload $plupload = null)
 {
 	global $auth, $user, $config, $db, $cache;
 	global $phpbb_root_path, $phpEx;
@@ -434,7 +435,7 @@ function upload_attachment($form_name, $forum_id, $local = false, $local_storage
 	$extensions = $cache->obtain_attach_extensions((($is_message) ? false : (int) $forum_id));
 	$upload->set_allowed_extensions(array_keys($extensions['_allowed_']));
 
-	$file = ($local) ? $upload->local_upload($local_storage, $local_filedata) : $upload->form_upload($form_name, $plupload);
+	$file = ($local) ? $upload->local_upload($local_storage, $local_filedata, $mimetype_guesser) : $upload->form_upload($form_name, $mimetype_guesser, $plupload);
 
 	if ($file->init_error)
 	{
diff --git a/phpBB/includes/message_parser.php b/phpBB/includes/message_parser.php
index 8d926ec70a..19571d6bd3 100644
--- a/phpBB/includes/message_parser.php
+++ b/phpBB/includes/message_parser.php
@@ -1082,6 +1082,12 @@ class parse_message extends bbcode_firstpass
 	*/
 	protected $plupload;
 
+	/**
+	* The mimetype guesser object used for attachment mimetypes
+	* @var \phpbb\mimetype\guesser
+	*/
+	protected $mimetype_guesser;
+
 	/**
 	* Init - give message here or manually
 	*/
@@ -1560,7 +1566,7 @@ class parse_message extends bbcode_firstpass
 			{
 				if ($num_attachments < $cfg['max_attachments'] || $auth->acl_gets('m_', 'a_', $forum_id))
 				{
-					$filedata = upload_attachment($form_name, $forum_id, false, '', $is_message, false, $this->plupload);
+					$filedata = upload_attachment($form_name, $forum_id, false, '', $is_message, false, $this->mimetype_guesser, $this->plupload);
 					$error = array_merge($error, $filedata['error']);
 
 					if (!sizeof($error))
@@ -1792,4 +1798,17 @@ class parse_message extends bbcode_firstpass
 	{
 		$this->plupload = $plupload;
 	}
+
+	/**
+	* Setter function for passing the mimetype_guesser object
+	*
+	* @param \phpbb\mimetype\guesser $mimetype_guesser The mimetype_guesser
+	*				object
+	*
+	* @return null
+	*/
+	public function set_mimetype_guesser(\phpbb\mimetype\guesser $mimetype_guesser)
+	{
+		$this->mimetype_guesser = $mimetype_guesser;
+	}
 }
diff --git a/phpBB/posting.php b/phpBB/posting.php
index 1b8fa6debf..0e912330e0 100644
--- a/phpBB/posting.php
+++ b/phpBB/posting.php
@@ -523,7 +523,9 @@ $orig_poll_options_size = sizeof($post_data['poll_options']);
 
 $message_parser = new parse_message();
 $plupload = $phpbb_container->get('plupload');
+$mimetype_guesser = $phpbb_container->get('mimetype.guesser');
 $message_parser->set_plupload($plupload);
+$message_parser->set_mimetype_guesser($mimetype_guesser);
 
 if (isset($post_data['post_text']))
 {