diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index d11e608..07b4459 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -26,6 +26,11 @@
 const DRUPAL_MINIMUM_PHP = '5.4.5';
 
 /**
+ * Suggested version of PHP.
+ */
+const DRUPAL_SUGGESTED_PHP = '5.6';
+
+/**
  * Minimum recommended value of PHP memory_limit.
  *
  * 64M was chosen as a minimum requirement in order to allow for additional
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index a0849b1..d54b546 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -85,6 +85,10 @@ function system_requirements($phase) {
     // If PHP is old, it's not safe to continue with the requirements check.
     return $requirements;
   }
+  elseif (version_compare($phpversion, DRUPAL_SUGGESTED_PHP) < 0) {
+    $requirements['php']['description'] = t('Your PHP installation is a little old. Drupal suggests using PHP %version.', array('%version' => DRUPAL_SUGGESTED_PHP));
+    $requirements['php']['severity'] = REQUIREMENT_WARNING;
+  }
 
   // Suggest to update to at least 5.5.21 or 5.6.5 for disabling multiple
   // statements.