diff --git a/composer.json b/composer.json
index c793951..5e5a1a2 100644
--- a/composer.json
+++ b/composer.json
@@ -25,6 +25,9 @@
       "dealerdirect/phpcodesniffer-composer-installer": true
     },
     "optimize-autoloader": true,
+    "platform": {
+      "php": "7.1"
+    },
     "platform-check": false,
     "sort-packages": true
   },