diff --git a/README.md b/README.md
index 2763b19..339629c 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,7 @@
 * Contributors:      Stefan Kalscheuer
 * Requires at least: 4.4
 * Tested up to:      4.8
+* Requires PHP:      5.5
 * Stable tag:        1.4.1
 * License:           GPLv2 or later
 * License URI:       http://www.gnu.org/licenses/gpl-2.0.html