diff --git a/composer.json b/composer.json
index 6beb9f7..b16780e 100644
--- a/composer.json
+++ b/composer.json
@@ -10,6 +10,7 @@
     ],
     "require": {
         "php": ">=5.4.0",
+        "ext-mongo": "^1.2.12",
         "league/flysystem": "~1.0"
     },
     "require-dev": {