diff --git a/solutions/object_oriented_design/parking_lot/parking_lot.py b/solutions/object_oriented_design/parking_lot/parking_lot.py
index 12fcd24..08852d9 100644
--- a/solutions/object_oriented_design/parking_lot/parking_lot.py
+++ b/solutions/object_oriented_design/parking_lot/parking_lot.py
@@ -64,7 +64,7 @@ class ParkingLot(object):
         self.levels = []  # List of Levels
 
     def park_vehicle(self, vehicle):
-        for level in levels:
+        for level in self.levels:
             if level.park_vehicle(vehicle):
                 return True
         return False