diff --git a/composer.json b/composer.json
index 460097f..5dade36 100644
--- a/composer.json
+++ b/composer.json
@@ -20,8 +20,8 @@
     },
     "require": {
         "php": "^7.0",
-        "symfony/serializer": "^3.1",
-        "symfony/yaml": "^3.1",
+        "symfony/serializer": "^3.1|^4.0",
+        "symfony/yaml": "^3.1|^4.0",
         "league/uri": "^4.2",
         "php-jsonpointer/php-jsonpointer": "^3.0"
     },