diff --git a/EGkGeomDB.h b/EGkGeomDB.h
index 422f905..86249c8 100644
--- a/EGkGeomDB.h
+++ b/EGkGeomDB.h
@@ -122,6 +122,7 @@ class __declspec( novtable) IGeomDB
       virtual bool EraseMaterial( int nMat, bool& bInUse) = 0 ;
       virtual bool GetMaterialData( int nMat, Material& matM) const = 0 ;
       virtual bool GetMaterialName( int nMat, std::string& sName) const = 0 ;
+      virtual int  GetMaxMaterialId( void) const = 0 ;
       virtual bool ExistsMaterial( int nMat) const = 0 ;
       virtual bool IsCustomMaterial( int nMat, bool& bCustom) const = 0 ;
       virtual bool ModifyMaterialData( int nMat, const Material& matM) = 0 ;