diff --git a/app/Concert.php b/app/Concert.php
index 31041e7..1ac6f44 100644
--- a/app/Concert.php
+++ b/app/Concert.php
@@ -58,7 +58,9 @@ class Concert extends Model
 
     public function reserveTickets($quantity)
     {
-        return $this->findTickets($quantity);
+        return $this->findTickets($quantity)->each(function ($ticket) {
+            $ticket->reserve();
+        });
     }
 
     public function findTickets($quantity)
diff --git a/app/Http/Controllers/ConcertOrdersController.php b/app/Http/Controllers/ConcertOrdersController.php
index baa3452..02d2832 100644
--- a/app/Http/Controllers/ConcertOrdersController.php
+++ b/app/Http/Controllers/ConcertOrdersController.php
@@ -31,7 +31,7 @@ class ConcertOrdersController extends Controller
 
         try {
             // Find some tickets
-            $tickets = $concert->findTickets(request('ticket_quantity'));
+            $tickets = $concert->reserveTickets(request('ticket_quantity'));
             $reservation = new Reservation($tickets);
 
             // Charge the customer for the tickets
diff --git a/app/Ticket.php b/app/Ticket.php
index 5e2f52b..e62d4e7 100644
--- a/app/Ticket.php
+++ b/app/Ticket.php
@@ -11,7 +11,7 @@ class Ticket extends Model
 
     public function scopeAvailable($query)
     {
-        return $query->whereNull('order_id');
+        return $query->whereNull('order_id')->whereNull('reserved_at');
     }
 
     public function reserve()
diff --git a/tests/unit/ConcertTest.php b/tests/unit/ConcertTest.php
index c717649..cd6d210 100644
--- a/tests/unit/ConcertTest.php
+++ b/tests/unit/ConcertTest.php
@@ -129,4 +129,36 @@ class ConcertTest extends TestCase
         $this->assertCount(2, $reservedTickets);
         $this->assertEquals(1, $concert->ticketsRemaining());
     }
+
+    /** @test */
+    function cannot_reserve_tickets_that_have_already_been_purchased()
+    {
+        $concert = factory(Concert::class)->create()->addTickets(3);
+        $concert->orderTickets('jane@example.com', 2);
+
+        try {
+            $concert->reserveTickets(2);
+        } catch (NotEnoughTicketsException $e) {
+            $this->assertEquals(1, $concert->ticketsRemaining());
+            return;
+        }
+
+        $this->fail("Reserving tickets succeeded even though the tickets were already sold.");
+    }
+
+    /** @test */
+    function cannot_reserve_tickets_that_have_already_been_reserved()
+    {
+        $concert = factory(Concert::class)->create()->addTickets(3);
+        $concert->reserveTickets(2);
+
+        try {
+            $concert->reserveTickets(2);
+        } catch (NotEnoughTicketsException $e) {
+            $this->assertEquals(1, $concert->ticketsRemaining());
+            return;
+        }
+
+        $this->fail("Reserving tickets succeeded even though the tickets were already reserved.");
+    }
 }