diff --git a/app/Models/CheckoutAcceptance.php b/app/Models/CheckoutAcceptance.php
index 9c501aaf63..b1c6c79141 100644
--- a/app/Models/CheckoutAcceptance.php
+++ b/app/Models/CheckoutAcceptance.php
@@ -70,7 +70,7 @@ class CheckoutAcceptance extends Model
      */
     public function isCheckedOutTo(User $user)
     {
-        return $this->assignedTo->is($user);
+        return $this->assignedTo?->is($user);
     }
 
     /**
diff --git a/tests/Feature/CheckoutAcceptances/Ui/AccessoryAcceptanceTest.php b/tests/Feature/CheckoutAcceptances/Ui/AccessoryAcceptanceTest.php
index 83ec916cb4..2390b16808 100644
--- a/tests/Feature/CheckoutAcceptances/Ui/AccessoryAcceptanceTest.php
+++ b/tests/Feature/CheckoutAcceptances/Ui/AccessoryAcceptanceTest.php
@@ -3,7 +3,9 @@
 namespace Tests\Feature\CheckoutAcceptances\Ui;
 
 use App\Models\Accessory;
+use App\Models\Asset;
 use App\Models\CheckoutAcceptance;
+use App\Models\User;
 use App\Notifications\AcceptanceAssetAcceptedNotification;
 use App\Notifications\AcceptanceAssetDeclinedNotification;
 use Notification;
@@ -76,4 +78,22 @@ class AccessoryAcceptanceTest extends TestCase
             }
         );
     }
+
+    public function testUserIsNotAbleToAcceptAnAssetAssignedToADifferentUser()
+    {
+        Notification::fake();
+
+        $otherUser = User::factory()->create();
+
+        $acceptance = CheckoutAcceptance::factory()
+            ->pending()
+            ->for(Asset::factory()->laptopMbp(), 'checkoutable')
+            ->create();
+
+        $this->actingAs($otherUser)
+            ->post(route('account.store-acceptance', $acceptance), ['asset_acceptance' => 'accepted'])
+            ->assertSessionHas(['error' => trans('admin/users/message.error.incorrect_user_accepted')]);
+
+        $this->assertNull($acceptance->fresh()->accepted_at);
+    }
 }