diff --git a/phpBB/install/convertors/functions_phpbb20.php b/phpBB/install/convertors/functions_phpbb20.php
index d7054b71e4..c139cf4189 100644
--- a/phpBB/install/convertors/functions_phpbb20.php
+++ b/phpBB/install/convertors/functions_phpbb20.php
@@ -1156,7 +1156,7 @@ function phpbb_prepare_message($message)
 		// Adjust size...
 		if (strpos($message, '[size=') !== false)
 		{
-			$message = preg_replace_callback('/\[size=(\d*):' . $convert->row['old_bbcode_uid'] . '\]/', 'replace_size', $message);
+			$message = preg_replace_callback('/\[size=(\d*):' . $convert->row['old_bbcode_uid'] . '\]/', 'phpbb_replace_size', $message);
 		}
 
 		$message = preg_replace('/\:(([a-z0-9]:)?)' . $convert->row['old_bbcode_uid'] . '/s', '', $message);