diff --git a/composer.json b/composer.json
index 9283d80..8ec5a3c 100644
--- a/composer.json
+++ b/composer.json
@@ -8,6 +8,7 @@
         "php"          : ">=7.0",
         "ext-mbstring" : "*",
         "ext-ctype"    : "*",
+        "ext-curl"     : "*",
         "sabre/event"  : ">=4.0 <6.0",
         "sabre/uri"    : "^2.0"
     },