diff --git a/composer.json b/composer.json
index 05e900c..fc00893 100644
--- a/composer.json
+++ b/composer.json
@@ -4,7 +4,7 @@
     "type": "flarum-extension",
     "license": "MIT",
     "require": {
-        "flarum/core": "^1.0"
+        "flarum/core": "^1.0|^2.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/RemoveEmailDriver.php b/src/RemoveEmailDriver.php
index f2a6fcc..932320e 100644
--- a/src/RemoveEmailDriver.php
+++ b/src/RemoveEmailDriver.php
@@ -8,7 +8,7 @@ use Illuminate\Contracts\Container\Container;
 
 class RemoveEmailDriver implements ExtenderInterface
 {
-    public function extend(Container $container, Extension $extension = null): void
+    public function extend(Container $container, ?Extension $extension = null): void
     {
         $container->extend('flarum.notification.drivers', function (array $drivers) {
             unset($drivers['email']);