diff --git a/EGkCurveAux.h b/EGkCurveAux.h
index 137fb1f..8fc8ac5 100644
--- a/EGkCurveAux.h
+++ b/EGkCurveAux.h
@@ -16,6 +16,9 @@
 #include "/EgtDev/Include/EGkCurveComposite.h"
 
 class ICurveBezier ;
+class ICurveLine ;
+class ICurveArc ;
+class ICurveComposite ;
 
 //----------------------- Macro per import/export ----------------------------
 #undef EGK_EXPORT