diff --git a/EGkCurve.h b/EGkCurve.h
index 7d20f16..52ca910 100644
--- a/EGkCurve.h
+++ b/EGkCurve.h
@@ -80,7 +80,7 @@ class __declspec( novtable) ICurve : public IGeoObj
       virtual bool ApproxWithArcsEx( double dLinTol, double dAngTolDeg, double dLinFea, PolyArc& PA) const = 0 ;
       virtual ICurve* CopyParamRange( double dUStart, double dUEnd) const = 0 ;
       virtual bool Invert( void) = 0 ;
-      virtual bool SimpleOffset( double dDist, int nType = OFF_FILLET) = 0 ;
+      virtual bool SimpleOffset( double dDist, int nType = OFF_FILLET, double dMaxAngExt = ANG_RIGHT) = 0 ;
       virtual bool SetExtrusion( const Vector3d& vtExtr) = 0 ;
       virtual bool SetThickness( double dThick) = 0 ;
       virtual bool ModifyStart( const Point3d& ptNewStart) = 0 ;
diff --git a/EGkCurveArc.h b/EGkCurveArc.h
index 9e879a0..2d28e2d 100644
--- a/EGkCurveArc.h
+++ b/EGkCurveArc.h
@@ -55,7 +55,7 @@ class __declspec( novtable) ICurveArc : public ICurve
       virtual bool ChangeDeltaN( double dNewDeltaN) = 0 ;
       virtual bool ChangeAngCenter( double dNewAngCenDeg) = 0 ;
       virtual bool ChangeStartPoint( double dU) = 0 ;
-      virtual bool ExtendedOffset( double dDist, int nType = OFF_FILLET) = 0 ;
+      virtual bool ExtendedOffset( double dDist) = 0 ;
       virtual bool ToExplementary( void) = 0 ;
       virtual bool Flip( void) = 0 ;
 } ;