diff --git a/apps/openmw/mwclass/door.cpp b/apps/openmw/mwclass/door.cpp
index 3d2719c58..58c33ba95 100644
--- a/apps/openmw/mwclass/door.cpp
+++ b/apps/openmw/mwclass/door.cpp
@@ -41,6 +41,10 @@ namespace MWClass
         {
             return *this;
         }
+        virtual const DoorCustomData& asDoorCustomData() const
+        {
+            return *this;
+        }
     };
 
     MWWorld::CustomData *DoorCustomData::clone() const
@@ -312,9 +316,10 @@ namespace MWClass
         }
     }
 
-    int Door::getDoorState (const MWWorld::Ptr &ptr) const
+    int Door::getDoorState (const MWWorld::ConstPtr &ptr) const
     {
-        ensureCustomData(ptr);
+        if (!ptr.getRefData().getCustomData())
+            return 0;
         const DoorCustomData& customData = ptr.getRefData().getCustomData()->asDoorCustomData();
         return customData.mDoorState;
     }
diff --git a/apps/openmw/mwclass/door.hpp b/apps/openmw/mwclass/door.hpp
index ff94cd613..74ab11fd9 100644
--- a/apps/openmw/mwclass/door.hpp
+++ b/apps/openmw/mwclass/door.hpp
@@ -53,7 +53,7 @@ namespace MWClass
             virtual std::string getModel(const MWWorld::ConstPtr &ptr) const;
 
             /// 0 = nothing, 1 = opening, 2 = closing
-            virtual int getDoorState (const MWWorld::Ptr &ptr) const;
+            virtual int getDoorState (const MWWorld::ConstPtr &ptr) const;
             /// This does not actually cause the door to move. Use World::activateDoor instead.
             virtual void setDoorState (const MWWorld::Ptr &ptr, int state) const;
 
diff --git a/apps/openmw/mwmechanics/aiavoiddoor.cpp b/apps/openmw/mwmechanics/aiavoiddoor.cpp
index 409f7b9c4..100b666e8 100644
--- a/apps/openmw/mwmechanics/aiavoiddoor.cpp
+++ b/apps/openmw/mwmechanics/aiavoiddoor.cpp
@@ -11,7 +11,7 @@
 
 #include "steering.hpp"
 
-MWMechanics::AiAvoidDoor::AiAvoidDoor(const MWWorld::Ptr& doorPtr)
+MWMechanics::AiAvoidDoor::AiAvoidDoor(const MWWorld::ConstPtr& doorPtr)
 : AiPackage(), mDuration(1), mDoorPtr(doorPtr), mAdjAngle(0)
 {
 
diff --git a/apps/openmw/mwmechanics/aiavoiddoor.hpp b/apps/openmw/mwmechanics/aiavoiddoor.hpp
index 1ad945bca..9d63c63e0 100644
--- a/apps/openmw/mwmechanics/aiavoiddoor.hpp
+++ b/apps/openmw/mwmechanics/aiavoiddoor.hpp
@@ -16,7 +16,7 @@ namespace MWMechanics
     {
         public:
             /// Avoid door until the door is fully open
-            AiAvoidDoor(const MWWorld::Ptr& doorPtr);
+            AiAvoidDoor(const MWWorld::ConstPtr& doorPtr);
 
             virtual AiAvoidDoor *clone() const;
 
@@ -28,7 +28,7 @@ namespace MWMechanics
 
         private:
             float mDuration;
-            MWWorld::Ptr mDoorPtr;
+            MWWorld::ConstPtr mDoorPtr;
             ESM::Position mLastPos;
             float mAdjAngle;
     };
diff --git a/apps/openmw/mwworld/class.cpp b/apps/openmw/mwworld/class.cpp
index 118bfe018..397762df8 100644
--- a/apps/openmw/mwworld/class.cpp
+++ b/apps/openmw/mwworld/class.cpp
@@ -404,7 +404,7 @@ namespace MWWorld
         return false;
     }
 
-    int Class::getDoorState (const MWWorld::Ptr &ptr) const
+    int Class::getDoorState (const MWWorld::ConstPtr &ptr) const
     {
         throw std::runtime_error("this is not a door");
     }
diff --git a/apps/openmw/mwworld/class.hpp b/apps/openmw/mwworld/class.hpp
index deee0f154..2ef0ba2d4 100644
--- a/apps/openmw/mwworld/class.hpp
+++ b/apps/openmw/mwworld/class.hpp
@@ -319,7 +319,7 @@ namespace MWWorld
             virtual bool isClass(const MWWorld::ConstPtr& ptr, const std::string &className) const;
 
             /// 0 = nothing, 1 = opening, 2 = closing
-            virtual int getDoorState (const MWWorld::Ptr &ptr) const;
+            virtual int getDoorState (const MWWorld::ConstPtr &ptr) const;
             /// This does not actually cause the door to move. Use World::activateDoor instead.
             virtual void setDoorState (const MWWorld::Ptr &ptr, int state) const;
 
diff --git a/apps/openmw/mwworld/customdata.cpp b/apps/openmw/mwworld/customdata.cpp
index dce1e9fdd..6f9fb39a7 100644
--- a/apps/openmw/mwworld/customdata.cpp
+++ b/apps/openmw/mwworld/customdata.cpp
@@ -42,6 +42,13 @@ MWClass::DoorCustomData &CustomData::asDoorCustomData()
     throw std::logic_error(error.str());
 }
 
+const MWClass::DoorCustomData &CustomData::asDoorCustomData() const
+{
+    std::stringstream error;
+    error << "bad cast " << typeid(this).name() << " to DoorCustomData";
+    throw std::logic_error(error.str());
+}
+
 MWClass::CreatureLevListCustomData &CustomData::asCreatureLevListCustomData()
 {
     std::stringstream error;
diff --git a/apps/openmw/mwworld/customdata.hpp b/apps/openmw/mwworld/customdata.hpp
index 407962ee0..4ca16fd32 100644
--- a/apps/openmw/mwworld/customdata.hpp
+++ b/apps/openmw/mwworld/customdata.hpp
@@ -31,6 +31,7 @@ namespace MWWorld
             virtual MWClass::ContainerCustomData& asContainerCustomData();
 
             virtual MWClass::DoorCustomData& asDoorCustomData();
+            virtual const MWClass::DoorCustomData& asDoorCustomData() const;
 
             virtual MWClass::CreatureLevListCustomData& asCreatureLevListCustomData();
     };