diff --git a/composer.json b/composer.json
index 6cdf52a..2a4f054 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,7 @@
         "php": "^7.2",
         "ext-dom": "*",
         "phpunit/phpunit": "^8.0",
-        "symfony/yaml": "^5.0"
+        "symfony/yaml": "^4.0|^5.0"
     },
     "autoload": {
         "psr-4": {