diff --git a/composer.json b/composer.json
index a82586a995..0ac864eb01 100644
--- a/composer.json
+++ b/composer.json
@@ -99,7 +99,7 @@
   },
   "scripts": {
     "pre-install-cmd": [
-      "if [ -z ${DYNO+x} ]; then echo Not in Heroku environment.; else php -r \"file_exists('.env') || copy('.env.heroku', '.env');\"; fi"
+      "php -r \"if (!(getenv('DYNO'))===false){file_exists('.env') || copy('.env.heroku', '.env');}else{echo 'Not in Heroku environment\n';}\""
     ],
     "post-root-package-install": [
       "@php -r \"file_exists('.env') || copy('.env.example', '.env');\""