diff --git a/Algebraic_kernel_d/include/CGAL/Algebraic_curve_kernel_2/Curve_pair_analysis_2.h b/Algebraic_kernel_d/include/CGAL/Algebraic_curve_kernel_2/Curve_pair_analysis_2.h
index 33df5cbfbef..5d05b9b86b3 100755
--- a/Algebraic_kernel_d/include/CGAL/Algebraic_curve_kernel_2/Curve_pair_analysis_2.h
+++ b/Algebraic_kernel_d/include/CGAL/Algebraic_curve_kernel_2/Curve_pair_analysis_2.h
@@ -234,19 +234,22 @@ public:
         Status_line_1 line(i, arcs, *this);
 
         CGAL_precondition_code(
-        int typo;
-        typename Status_line_1::Arc_pair pair;
-        for(int j = 0; j < slice.num_arcs(); j++) {
-
-            pair = line.curves_at_event(j);
-            if(pair.first != -1 && pair.second != -1)
-                typo = 2;
-            else 
-                typo = (pair.first != -1 ? 0 : 1);
-         /*std::cout << "[" << pair.first << "; " << pair.second << "] and "  <<
-                (int)(slice.arc_at_event(j).first) << "\n";*/
-            CGAL_precondition(typo == slice.arc_at_event(j).first);
-        }    
+                int typo;
+                typename Status_line_1::Arc_pair pair;
+                for (int j = 0; j < slice.num_arcs(); j++) {
+                    pair = line.curves_at_event(j);
+                    if (pair.first != -1 && pair.second != -1) {
+                        typo = 2;
+                    } else {
+                        typo = (pair.first != -1 ? 0 : 1);
+                        if (this->ptr()->_m_swapped) {
+                            typo = 1 - typo;
+                        }
+                    }
+                    /*std::cout << "[" << pair.first << "; " << pair.second << "] and "  <<
+                      (int)(slice.arc_at_event(j).first) << "\n";*/
+                    CGAL_precondition(typo == slice.arc_at_event(j).first);
+                }    
         );
         return line;
 #endif // CGAL_ACK_2_USE_STATUS_LINES
@@ -277,15 +280,18 @@ public:
         Status_line_1 line(i, arcs, *this);
 
         CGAL_precondition_code(
-         int typo;
-        typename Status_line_1::Arc_pair pair;
-        for(int j = 0; j < slice.num_arcs(); j++) {
-
-            pair = line.curves_at_event(j);
-            typo = (pair.first != -1 ? 0 : 1);
-            CGAL_precondition(typo == slice.arc_at_interval(j));
-        }    );
-
+                int typo;
+                typename Status_line_1::Arc_pair pair;
+                for (int j = 0; j < slice.num_arcs(); j++) {
+                    pair = line.curves_at_event(j);
+                    typo = (pair.first != -1 ? 0 : 1);
+                    if (this->ptr()->_m_swapped) {
+                        typo = 1 - typo;
+                    }
+                    CGAL_precondition(typo == slice.arc_at_interval(j));
+                }
+        );
+        
         return line;
 #endif // CGAL_ACK_2_USE_STATUS_LINES
     }