diff --git a/lib/environmentlib.php b/lib/environmentlib.php
index d547df7d32a..067b9cb41e3 100644
--- a/lib/environmentlib.php
+++ b/lib/environmentlib.php
@@ -482,6 +482,17 @@ function environment_check_php_extensions($version) {
         $result->setErrorCode(NO_PHP_EXTENSIONS_SECTION_FOUND);
         return array($result);
     }
+
+/// Hack alert: inject extra mysqli dependency, mysql PHP extension is not supported in Moodle 2.x, warn only ppl using MySQL.
+    global $CFG;
+    set_dbfamily();
+    if ($CFG->dbfamily === 'mysql') {
+        $mver = normalize_version($version);
+        if (version_compare($mver, '2.0', 'ge')) {
+            $data['#']['PHP_EXTENSIONS']['0']['#']['PHP_EXTENSION'][] = array('#' => '', '@' => array('name' => 'mysqli', 'level' => 'required'));
+        }
+    }
+
 /// Iterate over extensions checking them and creating the needed environment_results
     foreach($data['#']['PHP_EXTENSIONS']['0']['#']['PHP_EXTENSION'] as $extension) {
         $result = new environment_results('php_extension');