diff --git a/composer.json b/composer.json
index d91b02ee..4a1f6b9f 100644
--- a/composer.json
+++ b/composer.json
@@ -1,5 +1,11 @@
 {
     "require": {
+        "php": ">=5.5",
+        "ext-json": "*",
+        "ext-pdo": "*",
+        "ext-pdo_mysql": "*",
+        "ext-xml": "*",
+        "ext-zip": "*",
         "phpmailer/phpmailer": "^6.1",
         "composer/semver": "^3.2",
         "twig/twig": "~1.42.5"