diff --git a/src/Tenancy.php b/src/Tenancy.php
index 8e0ded99..86eb6d8d 100644
--- a/src/Tenancy.php
+++ b/src/Tenancy.php
@@ -136,7 +136,7 @@ class Tenancy
     public function getBootstrappers(): array
     {
         // If no callback for getting bootstrappers is set, we return the ones in config.
-        $resolve = $this->getBootstrappersUsing ?? function (Tenant $tenant) {
+        $resolve = $this->getBootstrappersUsing ?? function (?Tenant $tenant) {
             return config('tenancy.bootstrappers');
         };