diff --git a/GeoModelCore/GeoModelKernel/GeoModelKernel/GeoLogVol.h b/GeoModelCore/GeoModelKernel/GeoModelKernel/GeoLogVol.h
index c8578cb84b13053b4146684448debe36f514c6cf..2a214623383bdeee5d3e6a98235724f14f5fa42a 100644
--- a/GeoModelCore/GeoModelKernel/GeoModelKernel/GeoLogVol.h
+++ b/GeoModelCore/GeoModelKernel/GeoModelKernel/GeoLogVol.h
@@ -39,7 +39,7 @@ class GeoLogVol : public RCBase
   }
   
   //    In some cases (gases, liquids) materials be updated?
-  void setMaterial (const GeoMaterial *newMaterial) {
+  void setMaterial (const GeoMaterial *newMaterial) const {
     m_material=newMaterial;
   }
   
@@ -52,7 +52,7 @@ class GeoLogVol : public RCBase
   std::string m_name{};
 
   //	Material composition of this volume.
-  GeoIntrusivePtr<const GeoMaterial> m_material{};
+  mutable GeoIntrusivePtr<const GeoMaterial> m_material{};
 
   //	Shape of this volume.
   GeoIntrusivePtr<const GeoShape> m_shape{};
diff --git a/GeoModelExamples/KitchenSinkPlugin/src/KitchenSinkPlugin.cxx b/GeoModelExamples/KitchenSinkPlugin/src/KitchenSinkPlugin.cxx
index fd8e240f49f4b9660d3ac05e558f38406c4a2417..63174c04931c6fb767815f6deb76247bccdba3e6 100644
--- a/GeoModelExamples/KitchenSinkPlugin/src/KitchenSinkPlugin.cxx
+++ b/GeoModelExamples/KitchenSinkPlugin/src/KitchenSinkPlugin.cxx
@@ -294,7 +294,7 @@ void KitchenSinkPlugin::create(GeoVPhysVol *world, bool /*publish*/) {
     double height=platformHeight/2.0+barThickness/2.0+flangeThickness/2.0+barThickness;
     double xHalfLength=leftRightLegSeparation/2.0-barWidth1/2.0-cutoutWidth/2.0-barWidth2/2.0 ;
     const GeoBox       *wBox  = new GeoBox(xHalfLength, cutoutDepth/2.0    ,barThickness/2.0);
-    GeoLogVol    *wLog  = new GeoLogVol("WLog", wBox, Aluminium);
+    const GeoLogVol    *wLog  = new GeoLogVol("WLog", wBox, Aluminium);
     GeoPhysVol         *wPhys = new GeoPhysVol(wLog);
     GeoTransform       *wTransform = new GeoTransform(
 							 GeoTrf::Translate3D(-(61.0+11.0/16.0+4.0)/2.0+xHalfLength+4,0,height)