diff --git a/src/Encryption.php b/src/Encryption.php
index b0670e7..a6f4070 100644
--- a/src/Encryption.php
+++ b/src/Encryption.php
@@ -251,8 +251,10 @@ private static function createInfo(string $type, ?string $context, ContentEncodi
     private static function createLocalKeyObject(): array
     {
         $keyResource = openssl_pkey_new([
-            'curve_name'       => 'prime256v1',
-            'private_key_type' => OPENSSL_KEYTYPE_EC,
+            'ec' => [
+                'curve_name'       => 'prime256v1',
+                'private_key_type' => OPENSSL_KEYTYPE_EC,
+            ],
         ]);
         if (!$keyResource) {
             throw new \RuntimeException('Unable to create the local key.');