diff --git a/composer.json b/composer.json
index 638fb5ea..b34416fb 100644
--- a/composer.json
+++ b/composer.json
@@ -9,6 +9,7 @@
     }],
     "require": {
         "php": ">=5.4",
+        "ext-curl": "*",
         "ratchet/pawl": "^0.3.0",
         "react/socket": "^1.0 || ^0.8 || ^0.7",
         "ratchet/rfc6455": "^0.2.3",