diff --git a/composer.json b/composer.json
index 2fd064a..851fc7b 100644
--- a/composer.json
+++ b/composer.json
@@ -13,8 +13,14 @@
         }
     ],
     "require": {
-        "php": ">=7.0",
-        "ext-tokenizer": "*"
+        "php": ">=5.6",
+        "ext-tokenizer": "*",
+        "symfony/polyfill-php70": "*",
+        "symfony/polyfill-php71": "*",
+        "symfony/polyfill-php72": "*",
+        "symfony/polyfill-php73": "*",
+        "symfony/polyfill-php74": "*",
+        "symfony/polyfill-php80": "*"
     },
     "require-dev": {
         "phpunit/phpunit": "^6.5 || ^7.0 || ^8.0 || ^9.0",