diff --git a/composer.json b/composer.json
index dd54ea2..63400b2 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,7 @@
   "require": {
     "php": ">=7.0",
     "composer/installers": "^1.8",
-    "vlucas/phpdotenv": "^3.3.2",
+    "vlucas/phpdotenv": "^4.1.2",
     "johnpbloch/wordpress": "^5.3.2",
     "justcoded/wordpress-composer-scripts": "~1.2",
     "wpackagist-theme/twentyseventeen": "*",
diff --git a/environments/dotenv.php b/environments/dotenv.php
index 27067d4..715a0d6 100644
--- a/environments/dotenv.php
+++ b/environments/dotenv.php
@@ -13,7 +13,7 @@ function dotenv( $config = null ) {
 		static $dotenv;
 
 		if ( ! is_null( $config ) ) {
-			$dotenv = Dotenv\Dotenv::create( $config );
+			$dotenv = Dotenv\Dotenv::createImmutable( $config );
 		}
 
 		if ( ! $dotenv ) {