diff --git a/composer.json b/composer.json
index 3861c18..f3d45cf 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
         "symfony/config": "3.4",
         "symfony/process": "^3.4",
         "monolog/monolog": "^2.0",
-        "symfony/yaml": "^5.0"
+        "symfony/yaml": "~3.0|~4.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^7.4"