diff --git a/Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/MaterialProperties.h b/Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/MaterialProperties.h
index bb645a02b16fec2da0ab555988366c435cc3e832..e9a83ce35a6d6a425bd54a050a3e2967820a67a8 100755
--- a/Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/MaterialProperties.h
+++ b/Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/MaterialProperties.h
@@ -110,22 +110,22 @@ namespace Trk {
       float dEdX() const;
 
       /** Material averaging */
-      void addMaterial(const Material& mp, float dInX0) const; 
+      void addMaterial(const Material& mp, float dInX0); 
       
       /** Set Material */
-      void setMaterial(const Material& mp, float thickness=1.) const;
+      void setMaterial(const Material& mp, float thickness=1.);
                                                                                   
     protected:
       friend class ::MaterialPropertiesCnv_p1;
 
       /** Set dEdX       - important for material calibarion */
-      virtual void setDeDx(float dEdX) const;        
+      virtual void setDeDx(float dEdX);        
       
-      mutable Material   m_material;
+      Material   m_material;
       
-      mutable float      m_dInX0;      //!< thickness in units of radiation length
-      mutable float      m_dInL0;      //!< thickness in units of nuclear interaction length
-      mutable float      m_zOaTrTd;    //!< @f$ \frac{Z}{A}\cdot\rho\cdot d @f$ - in ATLAS units
+      float      m_dInX0;      //!< thickness in units of radiation length
+      float      m_dInL0;      //!< thickness in units of nuclear interaction length
+      float      m_zOaTrTd;    //!< @f$ \frac{Z}{A}\cdot\rho\cdot d @f$ - in ATLAS units
 
   };
 
diff --git a/Tracking/TrkDetDescr/TrkGeometry/src/MaterialProperties.cxx b/Tracking/TrkDetDescr/TrkGeometry/src/MaterialProperties.cxx
index dbe705b7008e81d98c56ba0676913fe4c2995c13..15d62b956253fb5d7a98f2665289975338020072 100755
--- a/Tracking/TrkDetDescr/TrkGeometry/src/MaterialProperties.cxx
+++ b/Tracking/TrkDetDescr/TrkGeometry/src/MaterialProperties.cxx
@@ -72,7 +72,7 @@ Trk::MaterialProperties& Trk::MaterialProperties::operator *=( float scale )
   return(*this);
 }
 
-void Trk::MaterialProperties::addMaterial(const Trk::Material& mat, float dInX0) const {
+void Trk::MaterialProperties::addMaterial(const Trk::Material& mat, float dInX0){
   
       //!< @todo update ?
       // averaging factors based on thickness
@@ -94,7 +94,7 @@ void Trk::MaterialProperties::addMaterial(const Trk::Material& mat, float dInX0)
       m_zOaTrTd = m_material.A > 0 ? m_dInX0*m_material.X0*m_material.Z/m_material.A*m_material.rho : 0;      
 }
 
-void Trk::MaterialProperties::setMaterial(const Trk::Material& mat, float thickness) const {
+void Trk::MaterialProperties::setMaterial(const Trk::Material& mat, float thickness) {
     // just overwrite what you have
     m_material = mat;
     m_dInX0    = thickness/mat.X0;
@@ -102,7 +102,7 @@ void Trk::MaterialProperties::setMaterial(const Trk::Material& mat, float thickn
     m_zOaTrTd   = mat.Z/mat.A*mat.rho*thickness;
 }
 
-void Trk::MaterialProperties::setDeDx(float dEdX) const
+void Trk::MaterialProperties::setDeDx(float dEdX)
 {
     // set the DE/DX value
     m_material.dEdX = dEdX;