diff --git a/README.md b/README.md
index 40671eb..6dad292 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,7 @@ related pull requests are greatly welcomed.
 ## Requirements
 
 * PHP 5.3.23+
+* Not currently certified for use with HHVM (unit tests failing when run in an HHVM environment).
 
 ## Installation
 `composer require rotexsoft/file-renderer`