diff --git a/libraries/common.inc.php b/libraries/common.inc.php
index e860299e9..c5c66e129 100644
--- a/libraries/common.inc.php
+++ b/libraries/common.inc.php
@@ -59,7 +59,12 @@ require_once './libraries/sanitizing.lib.php';
 
 /**
  * the PMA_Theme class
+ * (this one is the first to produce a fatal error under PHP < 5)
  */
+if (version_compare(PHP_VERSION, '5.0.0') < 0 ) {
+    PMA_fatalError('strUpgrade', array('PHP', '5'));
+}
+
 require_once './libraries/Theme.class.php';
 
 /**