diff --git a/apps/openmw/mwphysics/physicssystem.cpp b/apps/openmw/mwphysics/physicssystem.cpp
index 15cb39fb1..d2d95d937 100644
--- a/apps/openmw/mwphysics/physicssystem.cpp
+++ b/apps/openmw/mwphysics/physicssystem.cpp
@@ -68,8 +68,8 @@ namespace MWPhysics
             return osg::RadiansToDegrees(std::acos(normal * osg::Vec3f(0.f, 0.f, 1.f)));
         }
 
-        static bool stepMove(btCollisionObject *colobj, osg::Vec3f &position,
-                             const osg::Vec3f &toMove, float &remainingTime, btCollisionWorld* collisionWorld)
+        static bool stepMove(const btCollisionObject *colobj, osg::Vec3f &position,
+                             const osg::Vec3f &toMove, float &remainingTime, const btCollisionWorld* collisionWorld)
         {
             /*
              * Slide up an incline or set of stairs.  Should be called only after a
@@ -235,7 +235,7 @@ namespace MWPhysics
         }
 
         static osg::Vec3f move(osg::Vec3f position, const MWWorld::Ptr &ptr, Actor* physicActor, const osg::Vec3f &movement, float time,
-                                  bool isFlying, float waterlevel, float slowFall, btCollisionWorld* collisionWorld,
+                                  bool isFlying, float waterlevel, float slowFall, const btCollisionWorld* collisionWorld,
                                std::map<MWWorld::Ptr, MWWorld::Ptr>& standingCollisionTracker)
         {
             const ESM::Position& refpos = ptr.getRefData().getPosition();
@@ -254,7 +254,7 @@ namespace MWPhysics
                                     ) * movement * time;
             }
 
-            btCollisionObject *colobj = physicActor->getCollisionObject();
+            const btCollisionObject *colobj = physicActor->getCollisionObject();
             osg::Vec3f halfExtents = physicActor->getHalfExtents();
 
             // NOTE: here we don't account for the collision box translation (i.e. physicActor->getPosition() - refpos.pos).
diff --git a/apps/openmw/mwphysics/trace.cpp b/apps/openmw/mwphysics/trace.cpp
index 94434b856..420ca1a9e 100644
--- a/apps/openmw/mwphysics/trace.cpp
+++ b/apps/openmw/mwphysics/trace.cpp
@@ -16,7 +16,7 @@ namespace MWPhysics
 class ClosestNotMeConvexResultCallback : public btCollisionWorld::ClosestConvexResultCallback
 {
 public:
-    ClosestNotMeConvexResultCallback(btCollisionObject *me, const btVector3 &up, btScalar minSlopeDot)
+    ClosestNotMeConvexResultCallback(const btCollisionObject *me, const btVector3 &up, btScalar minSlopeDot)
       : btCollisionWorld::ClosestConvexResultCallback(btVector3(0.0, 0.0, 0.0), btVector3(0.0, 0.0, 0.0)),
         mMe(me), mUp(up), mMinSlopeDot(minSlopeDot)
     {
@@ -44,13 +44,13 @@ public:
     }
 
 protected:
-    btCollisionObject *mMe;
+    const btCollisionObject *mMe;
     const btVector3 mUp;
     const btScalar mMinSlopeDot;
 };
 
 
-void ActorTracer::doTrace(btCollisionObject *actor, const osg::Vec3f& start, const osg::Vec3f& end, btCollisionWorld* world)
+void ActorTracer::doTrace(const btCollisionObject *actor, const osg::Vec3f& start, const osg::Vec3f& end, const btCollisionWorld* world)
 {
     const btVector3 btstart = toBullet(start);
     const btVector3 btend = toBullet(end);
@@ -66,9 +66,9 @@ void ActorTracer::doTrace(btCollisionObject *actor, const osg::Vec3f& start, con
     newTraceCallback.m_collisionFilterGroup = actor->getBroadphaseHandle()->m_collisionFilterGroup;
     newTraceCallback.m_collisionFilterMask = actor->getBroadphaseHandle()->m_collisionFilterMask;
 
-    btCollisionShape *shape = actor->getCollisionShape();
+    const btCollisionShape *shape = actor->getCollisionShape();
     assert(shape->isConvex());
-    world->convexSweepTest(static_cast<btConvexShape*>(shape),
+    world->convexSweepTest(static_cast<const btConvexShape*>(shape),
                                                from, to, newTraceCallback);
 
     // Copy the hit data over to our trace results struct:
@@ -89,7 +89,7 @@ void ActorTracer::doTrace(btCollisionObject *actor, const osg::Vec3f& start, con
     }
 }
 
-void ActorTracer::findGround(const Actor* actor, const osg::Vec3f& start, const osg::Vec3f& end, btCollisionWorld* world)
+void ActorTracer::findGround(const Actor* actor, const osg::Vec3f& start, const osg::Vec3f& end, const btCollisionWorld* world)
 {
     const btVector3 btstart(start.x(), start.y(), start.z()+1.0f);
     const btVector3 btend(end.x(), end.y(), end.z()+1.0f);
diff --git a/apps/openmw/mwphysics/trace.h b/apps/openmw/mwphysics/trace.h
index ef1a24d44..7b7d0391e 100644
--- a/apps/openmw/mwphysics/trace.h
+++ b/apps/openmw/mwphysics/trace.h
@@ -19,8 +19,8 @@ namespace MWPhysics
 
         float mFraction;
 
-        void doTrace(btCollisionObject *actor, const osg::Vec3f& start, const osg::Vec3f& end, btCollisionWorld* world);
-        void findGround(const Actor* actor, const osg::Vec3f& start, const osg::Vec3f& end, btCollisionWorld* world);
+        void doTrace(const btCollisionObject *actor, const osg::Vec3f& start, const osg::Vec3f& end, const btCollisionWorld* world);
+        void findGround(const Actor* actor, const osg::Vec3f& start, const osg::Vec3f& end, const btCollisionWorld* world);
     };
 }