diff --git a/core/update.php b/core/update.php
index e7e4e5c..f6f8414 100644
--- a/core/update.php
+++ b/core/update.php
@@ -22,6 +22,15 @@ chdir('..');
  */
 define('DRUPAL_ROOT', getcwd());
 
+// Exit early if running an incompatible PHP version to avoid fatal errors.
+// The minimum version is specified explicitly, as DRUPAL_MINIMUM_PHP is not
+// yet available. It is defined in bootstrap.inc, but it is not possible to
+// load that file yet as it would cause a fatal error on older versions of PHP.
+if (version_compare(PHP_VERSION, '5.3.2') < 0) {
+  print 'Your PHP installation is too old. Drupal requires at least PHP 5.3.2. See the <a href="http://drupal.org/requirements">system requirements</a> page for more information.';
+  exit;
+}
+
 /**
  * Global flag indicating that update.php is being run.
  *