diff --git a/DetectorDescription/Core/interface/DDCompactView.h b/DetectorDescription/Core/interface/DDCompactView.h
index a3d05c46628e4..e2f6a03963b80 100644
--- a/DetectorDescription/Core/interface/DDCompactView.h
+++ b/DetectorDescription/Core/interface/DDCompactView.h
@@ -113,7 +113,7 @@ class DDCompactView
   const DDLogicalPart & root() const;
   
   //! The absolute position of the world
-  DDPosData * worldPosition() const;
+  const DDPosData * worldPosition() const;
 
   //! Prototype version of calculating the weight of a detector component
   double weight(const DDLogicalPart & p) const;
diff --git a/DetectorDescription/Core/interface/DDExpandedNode.h b/DetectorDescription/Core/interface/DDExpandedNode.h
index ecdf1d8d5fd45..0c3a9e3285145 100644
--- a/DetectorDescription/Core/interface/DDExpandedNode.h
+++ b/DetectorDescription/Core/interface/DDExpandedNode.h
@@ -17,7 +17,7 @@ class DDExpandedNode
 
 public:
   DDExpandedNode(const DDLogicalPart & lp, 
-                 DDPosData * pd, 
+                 const DDPosData * pd, 
 	         const DDTranslation & t, 
 	         const DDRotationMatrix & r,
 		 int siblingno);
@@ -49,7 +49,7 @@ class DDExpandedNode
    
 private:
   DDLogicalPart logp_; // logicalpart to provide access to solid & material information
-  DDPosData * posd_;
+  const DDPosData * posd_;
   DDTranslation trans_;  // absolute translation
   DDRotationMatrix rot_; // absolute rotation
   int siblingno_; // internal sibling-numbering from 0 to max-sibling
diff --git a/DetectorDescription/Core/interface/DDExpandedView.h b/DetectorDescription/Core/interface/DDExpandedView.h
index 0bb0228a2a542..44c5847237e6a 100644
--- a/DetectorDescription/Core/interface/DDExpandedView.h
+++ b/DetectorDescription/Core/interface/DDExpandedView.h
@@ -133,7 +133,7 @@ class DDExpandedView
   DDGeoHistory history_; //!< std::vector of DDExpandedNode
   DDGeoHistory scope_; //!< scope of the expanded view
   unsigned int depth_; //!< depth of the scope, 0==unrestricted depth
-  DDPosData * worldpos_ ; //!< ???
+  const DDPosData * worldpos_ ; //!< ???
   std::vector<nav_type> nextBStack_;
 };
 
diff --git a/DetectorDescription/Core/src/DDCompactView.cc b/DetectorDescription/Core/src/DDCompactView.cc
index 66ce4553cfd7a..f198488891f88 100644
--- a/DetectorDescription/Core/src/DDCompactView.cc
+++ b/DetectorDescription/Core/src/DDCompactView.cc
@@ -69,7 +69,7 @@ const DDLogicalPart & DDCompactView::root() const
   return rep_->root(); 
 } 
   
-DDPosData* DDCompactView::worldPosition() const
+const DDPosData* DDCompactView::worldPosition() const
 {
   return worldpos_.get();
 }
diff --git a/DetectorDescription/Core/src/DDExpandedNode.cc b/DetectorDescription/Core/src/DDExpandedNode.cc
index 193ef89ad9246..142db12168109 100644
--- a/DetectorDescription/Core/src/DDExpandedNode.cc
+++ b/DetectorDescription/Core/src/DDExpandedNode.cc
@@ -2,7 +2,7 @@
 #include "DetectorDescription/Core/interface/DDPosData.h"
 
 DDExpandedNode::DDExpandedNode(const DDLogicalPart & lp, 
-                               DDPosData * pd, 
+                               const DDPosData * pd, 
 	                       const DDTranslation & t, 
 	                       const DDRotationMatrix & r,
 			       int siblingno)
diff --git a/DetectorDescription/Core/src/DDExpandedView.cc b/DetectorDescription/Core/src/DDExpandedView.cc
index 1c69d74c85034..912b55547c970 100644
--- a/DetectorDescription/Core/src/DDExpandedView.cc
+++ b/DetectorDescription/Core/src/DDExpandedView.cc
@@ -14,7 +14,7 @@ DDExpandedView::DDExpandedView( const DDCompactView & cpv )
 {
   walker_ = &w2_;
 
-  DDPosData * pd((*walker_).current().second);
+  const DDPosData * pd((*walker_).current().second);
   if (!pd)
     pd = worldpos_;
   DDExpandedNode expn((*walker_).current().first,