diff --git a/lib/testing/lib.php b/lib/testing/lib.php
index bbb93d3e293..de9db16bca6 100644
--- a/lib/testing/lib.php
+++ b/lib/testing/lib.php
@@ -193,7 +193,7 @@ function testing_update_composer_dependencies() {
     }
 
     // Update composer dependencies.
-    passthru("php composer.phar update", $code);
+    passthru("php composer.phar install", $code);
     if ($code != 0) {
         exit($code);
     }