diff --git a/phpBB/phpbb/mimetype/content_guesser.php b/phpBB/phpbb/mimetype/content_guesser.php
index 6326bf73fa..f5be9cd44b 100644
--- a/phpBB/phpbb/mimetype/content_guesser.php
+++ b/phpBB/phpbb/mimetype/content_guesser.php
@@ -21,7 +21,7 @@ if (!defined('IN_PHPBB'))
 * @package mimetype
 */
 
-class content_guesser
+class content_guesser implements guesser_interface
 {
 	/**
 	* @var file extension map
@@ -486,11 +486,7 @@ class content_guesser
 	}
 
 	/**
-	* Guess mimetype of supplied file
-	*
-	* @param string $file Path to file
-	*
-	* @return string Guess for mimetype of file
+	* @inheritdoc
 	*/
 	public function guess($file, $file_name = '')
 	{
diff --git a/phpBB/phpbb/mimetype/guesser_interface.php b/phpBB/phpbb/mimetype/guesser_interface.php
new file mode 100644
index 0000000000..a9b238d7aa
--- /dev/null
+++ b/phpBB/phpbb/mimetype/guesser_interface.php
@@ -0,0 +1,41 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+namespace phpbb\mimetype;
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* @package mimetype
+*/
+
+interface guesser_interface
+{
+	/**
+	* Returns whether this guesser is supported on the current OS
+	*
+	* @return bool True if guesser is supported, false if not
+	*/
+	public function is_supported();
+
+	/**
+	* Guess mimetype of supplied file
+	*
+	* @param string $file Path to file
+	*
+	* @return string Guess for mimetype of file
+	*/
+	public function guess($file, $file_name = '');
+}