diff --git a/composer.json b/composer.json
index d65ce55..2afaf1d 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,8 @@
   },
   "minimum-stability": "stable",
   "require": {
-    "php": ">=5.6.0"
+    "php": ">=5.6.0",
+    "ext-curl": "*"
   },
   "require-dev": {
     "phpunit/phpunit": "^4.8.30"