diff --git a/apps/openmw/mwclass/container.cpp b/apps/openmw/mwclass/container.cpp
index 03c676b9e..39ce594ae 100644
--- a/apps/openmw/mwclass/container.cpp
+++ b/apps/openmw/mwclass/container.cpp
@@ -279,7 +279,7 @@ namespace MWClass
         ptr.getCellRef().setLockLevel(-abs(ptr.getCellRef().getLockLevel())); //Makes lockLevel negative
     }
 
-    bool Container::canLock(const MWWorld::Ptr &ptr) const
+    bool Container::canLock(const MWWorld::ConstPtr &ptr) const
     {
         return true;
     }
diff --git a/apps/openmw/mwclass/container.hpp b/apps/openmw/mwclass/container.hpp
index 9b6d5d2e0..53795b540 100644
--- a/apps/openmw/mwclass/container.hpp
+++ b/apps/openmw/mwclass/container.hpp
@@ -56,7 +56,7 @@ namespace MWClass
             virtual void unlock (const MWWorld::Ptr& ptr) const;
             ///< Unlock object
 
-            virtual bool canLock(const MWWorld::Ptr &ptr) const;
+            virtual bool canLock(const MWWorld::ConstPtr &ptr) const;
 
             virtual void readAdditionalState (const MWWorld::Ptr& ptr, const ESM::ObjectState& state)
                 const;
diff --git a/apps/openmw/mwclass/door.cpp b/apps/openmw/mwclass/door.cpp
index f279ae3a0..dfd974ef6 100644
--- a/apps/openmw/mwclass/door.cpp
+++ b/apps/openmw/mwclass/door.cpp
@@ -209,7 +209,7 @@ namespace MWClass
         ptr.getCellRef().setLockLevel(-abs(ptr.getCellRef().getLockLevel())); //Makes lockLevel negative
     }
 
-    bool Door::canLock(const MWWorld::Ptr &ptr) const
+    bool Door::canLock(const MWWorld::ConstPtr &ptr) const
     {
         return true;
     }
diff --git a/apps/openmw/mwclass/door.hpp b/apps/openmw/mwclass/door.hpp
index f789055ff..7db9852db 100644
--- a/apps/openmw/mwclass/door.hpp
+++ b/apps/openmw/mwclass/door.hpp
@@ -46,7 +46,7 @@ namespace MWClass
             virtual void unlock (const MWWorld::Ptr& ptr) const;
             ///< Unlock object
 
-            virtual bool canLock(const MWWorld::Ptr &ptr) const;
+            virtual bool canLock(const MWWorld::ConstPtr &ptr) const;
 
             virtual std::string getScript (const MWWorld::ConstPtr& ptr) const;
             ///< Return name of the script attached to ptr
diff --git a/apps/openmw/mwworld/class.cpp b/apps/openmw/mwworld/class.cpp
index 6e699dd97..e4bb72283 100644
--- a/apps/openmw/mwworld/class.cpp
+++ b/apps/openmw/mwworld/class.cpp
@@ -143,7 +143,7 @@ namespace MWWorld
         throw std::runtime_error ("class does not support unlocking");
     }
 
-    bool Class::canLock(const Ptr &ptr) const
+    bool Class::canLock(const ConstPtr &ptr) const
     {
         return false;
     }
diff --git a/apps/openmw/mwworld/class.hpp b/apps/openmw/mwworld/class.hpp
index 943cfc451..0129a3dcf 100644
--- a/apps/openmw/mwworld/class.hpp
+++ b/apps/openmw/mwworld/class.hpp
@@ -161,7 +161,7 @@ namespace MWWorld
             virtual void unlock (const Ptr& ptr) const;
             ///< Unlock object (default implementation: throw an exception)
 
-            virtual bool canLock (const Ptr& ptr) const;
+            virtual bool canLock (const ConstPtr& ptr) const;
 
             virtual void setRemainingUsageTime (const Ptr& ptr, float duration) const;
             ///< Sets the remaining duration of the object, such as an equippable light