diff --git a/Algebraic_foundations/test/Algebraic_foundations/Chinese_remainder_traits.cpp b/Algebraic_foundations/test/Algebraic_foundations/Chinese_remainder_traits.cpp
index 11c967f563c..b3f30e815f4 100644
--- a/Algebraic_foundations/test/Algebraic_foundations/Chinese_remainder_traits.cpp
+++ b/Algebraic_foundations/test/Algebraic_foundations/Chinese_remainder_traits.cpp
@@ -47,12 +47,12 @@ struct Get_max_coefficient{
     }
 };
 
-template <class NT, class Root>
-struct Get_max_coefficient<CGAL::Sqrt_extension<NT, Root> >{        
+template <class NT, class Root,class ACDE_TAG, class FP_TAG>
+struct Get_max_coefficient<CGAL::Sqrt_extension<NT, Root, ACDE_TAG, FP_TAG> >{        
     typedef Get_max_coefficient<NT> GMC;
     typedef typename GMC::result_type result_type;
     
-    result_type operator () (const CGAL::Sqrt_extension<NT, Root>& a) {             
+    result_type operator () (const CGAL::Sqrt_extension<NT, Root, ACDE_TAG, FP_TAG>& a) {             
         GMC gmc;
         return std::max(std::max(gmc(a.a0()), gmc(a.a1())), gmc(NT(a.root())));            
     }
diff --git a/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_traits.h b/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_traits.h
index 01edf0a0c3e..2503d229e9b 100644
--- a/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_traits.h
+++ b/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_traits.h
@@ -153,9 +153,9 @@ struct Curve_renderer_traits_base
     struct Rat_to_float {
         typedef Float result_type;
 
-        template <class X, class Y>
-        Float operator()(const Sqrt_extension<X, Y>& x) const { 
-            typename CGAL::Coercion_traits<Sqrt_extension<X, Y>, Float>::Cast
+        template <class X, class Y,class ACDE_TAG,class FP_TAG>
+        Float operator()(const Sqrt_extension<X, Y, ACDE_TAG, FP_TAG>& x) const { 
+            typename CGAL::Coercion_traits<Sqrt_extension<X, Y, ACDE_TAG, FP_TAG>, Float>::Cast
                 cast;        
             return cast(x); 
         }
@@ -502,9 +502,9 @@ struct Curve_renderer_traits<leda::bigfloat, class leda::rational>
     struct Rat_to_float {
         typedef Float result_type;
 
-        template <class X, class Y>
-        Float operator()(const Sqrt_extension<X, Y>& x) const { 
-            typename CGAL::Coercion_traits<Sqrt_extension<X, Y>, Float>::Cast
+        template <class X, class Y,class ACDE_TAG,class FP_TAG>
+        Float operator()(const Sqrt_extension<X, Y, ACDE_TAG, FP_TAG>& x) const { 
+            typename CGAL::Coercion_traits<Sqrt_extension<X, Y, ACDE_TAG, FP_TAG>, Float>::Cast
                 cast;        
             return cast(x); 
         }
diff --git a/Number_types/include/CGAL/Sqrt_extension/Algebraic_extension_traits.h b/Number_types/include/CGAL/Sqrt_extension/Algebraic_extension_traits.h
index 01ebc0293f7..f77a951ad8f 100644
--- a/Number_types/include/CGAL/Sqrt_extension/Algebraic_extension_traits.h
+++ b/Number_types/include/CGAL/Sqrt_extension/Algebraic_extension_traits.h
@@ -43,11 +43,11 @@ class Algebraic_extension_traits<CGAL::Sqrt_extension<COEFF,ROOT,ACDE_TAG,FP_TAG
         }
     };
     
-  template <class COEFF_, class ROOT_>
-  class Standardise<CGAL::Sqrt_extension<COEFF_,ROOT_,ACDE_TAG,FP_TAG> > {
+  template <class COEFF_, class ROOT_,class ACDE_TAG_,class FP_TAG_>
+  class Standardise<CGAL::Sqrt_extension<COEFF_,ROOT_,ACDE_TAG_,FP_TAG_> > {
         Standardise<COEFF_> standardise;
     public:
-    typedef CGAL::Sqrt_extension<COEFF_,ROOT_,ACDE_TAG,FP_TAG> Type_;
+    typedef CGAL::Sqrt_extension<COEFF_,ROOT_,ACDE_TAG_,FP_TAG_> Type_;
         typedef Type_ argument_type;
         typedef Type_ result_type;
     Type_ operator () (const Type_& a) const {       
diff --git a/Number_types/include/CGAL/Sqrt_extension/Sqrt_extension_type.h b/Number_types/include/CGAL/Sqrt_extension/Sqrt_extension_type.h
index b95a0d11521..3e3338c086b 100644
--- a/Number_types/include/CGAL/Sqrt_extension/Sqrt_extension_type.h
+++ b/Number_types/include/CGAL/Sqrt_extension/Sqrt_extension_type.h
@@ -212,6 +212,12 @@ public:
     }
   }
 
+  
+  Self conjugate() const
+  {
+    if(!is_extended_) return *this;
+    return Self(a0_,-a1_,root_);
+  }
 
     //! Access operator for a0_, \c const
     inline const NT& a0() const { return a0_; }
diff --git a/Number_types/test/Number_types/root_of_2.cpp b/Number_types/test/Number_types/root_of_2.cpp
index 28b81e1c66c..1cfcd342fed 100644
--- a/Number_types/test/Number_types/root_of_2.cpp
+++ b/Number_types/test/Number_types/root_of_2.cpp
@@ -60,13 +60,13 @@ NT my_rand()
 
 //----------------------
 
-template<class T>
-bool is_RO2_class(const CGAL::Sqrt_extension<T,T>& ){ return true;}
+template<class T,class ACDE_TAG,class FP_TAG>
+bool is_RO2_class(const CGAL::Sqrt_extension<T,T,ACDE_TAG,FP_TAG>& ){ return true;}
 template<class T>
 bool is_RO2_class(const T& ){ return false;}
 
-template<class T>
-CGAL::Sqrt_extension<T,T> conjugate(const CGAL::Sqrt_extension<T,T>& R){
+template<class T,class ACDE_TAG,class FP_TAG>
+CGAL::Sqrt_extension<T,T,ACDE_TAG,FP_TAG> conjugate(const CGAL::Sqrt_extension<T,T,ACDE_TAG,FP_TAG>& R){
   return R.conjugate();
 }