diff --git a/apps/openmw/mwbase/world.hpp b/apps/openmw/mwbase/world.hpp
index 05b6454a3..9ee9db48c 100644
--- a/apps/openmw/mwbase/world.hpp
+++ b/apps/openmw/mwbase/world.hpp
@@ -409,9 +409,9 @@ namespace MWBase
 
             virtual float getWindSpeed() = 0;
 
-            virtual void getContainersOwnedBy (const MWWorld::Ptr& npc, std::vector<MWWorld::Ptr>& out) = 0;
+            virtual void getContainersOwnedBy (const MWWorld::ConstPtr& npc, std::vector<MWWorld::Ptr>& out) = 0;
             ///< get all containers in active cells owned by this Npc
-            virtual void getItemsOwnedBy (const MWWorld::Ptr& npc, std::vector<MWWorld::Ptr>& out) = 0;
+            virtual void getItemsOwnedBy (const MWWorld::ConstPtr& npc, std::vector<MWWorld::Ptr>& out) = 0;
             ///< get all items in active cells owned by this Npc
 
             virtual bool getLOS(const MWWorld::Ptr& actor,const MWWorld::Ptr& targetActor) = 0;
diff --git a/apps/openmw/mwworld/worldimp.cpp b/apps/openmw/mwworld/worldimp.cpp
index d19e311f5..357d50845 100644
--- a/apps/openmw/mwworld/worldimp.cpp
+++ b/apps/openmw/mwworld/worldimp.cpp
@@ -2260,13 +2260,13 @@ namespace MWWorld
 
     struct GetContainersOwnedByVisitor
     {
-        GetContainersOwnedByVisitor(const MWWorld::Ptr& owner, std::vector<MWWorld::Ptr>& out)
+        GetContainersOwnedByVisitor(const MWWorld::ConstPtr& owner, std::vector<MWWorld::Ptr>& out)
             : mOwner(owner)
             , mOut(out)
         {
         }
 
-        MWWorld::Ptr mOwner;
+        MWWorld::ConstPtr mOwner;
         std::vector<MWWorld::Ptr>& mOut;
 
         bool operator()(const MWWorld::Ptr& ptr)
@@ -2281,7 +2281,7 @@ namespace MWWorld
         }
     };
 
-    void World::getContainersOwnedBy (const MWWorld::Ptr& owner, std::vector<MWWorld::Ptr>& out)
+    void World::getContainersOwnedBy (const MWWorld::ConstPtr& owner, std::vector<MWWorld::Ptr>& out)
     {
         const Scene::CellStoreCollection& collection = mWorldScene->getActiveCells();
         for (Scene::CellStoreCollection::const_iterator cellIt = collection.begin(); cellIt != collection.end(); ++cellIt)
@@ -2303,7 +2303,7 @@ namespace MWWorld
         }
     };
 
-    void World::getItemsOwnedBy (const MWWorld::Ptr& npc, std::vector<MWWorld::Ptr>& out)
+    void World::getItemsOwnedBy (const MWWorld::ConstPtr& npc, std::vector<MWWorld::Ptr>& out)
     {
         const Scene::CellStoreCollection& collection = mWorldScene->getActiveCells();
         for (Scene::CellStoreCollection::const_iterator cellIt = collection.begin(); cellIt != collection.end(); ++cellIt)
diff --git a/apps/openmw/mwworld/worldimp.hpp b/apps/openmw/mwworld/worldimp.hpp
index ba3993c24..55932981e 100644
--- a/apps/openmw/mwworld/worldimp.hpp
+++ b/apps/openmw/mwworld/worldimp.hpp
@@ -513,9 +513,9 @@ namespace MWWorld
 
             virtual float getWindSpeed();
 
-            virtual void getContainersOwnedBy (const MWWorld::Ptr& npc, std::vector<MWWorld::Ptr>& out);
+            virtual void getContainersOwnedBy (const MWWorld::ConstPtr& npc, std::vector<MWWorld::Ptr>& out);
             ///< get all containers in active cells owned by this Npc
-            virtual void getItemsOwnedBy (const MWWorld::Ptr& npc, std::vector<MWWorld::Ptr>& out);
+            virtual void getItemsOwnedBy (const MWWorld::ConstPtr& npc, std::vector<MWWorld::Ptr>& out);
             ///< get all items in active cells owned by this Npc
 
             virtual bool getLOS(const MWWorld::Ptr& actor,const MWWorld::Ptr& targetActor);