diff --git a/Apollonius_graph_2/include/CGAL/Parabola_segment_2.h b/Apollonius_graph_2/include/CGAL/Parabola_segment_2.h
index 7c03ff5d5e5..cb74c18204d 100644
--- a/Apollonius_graph_2/include/CGAL/Parabola_segment_2.h
+++ b/Apollonius_graph_2/include/CGAL/Parabola_segment_2.h
@@ -63,7 +63,7 @@ public:
   }
 
   int compute_k(const FT tt, const FT STEP) const {
-    return int(CGAL::to_double(CGAL::sqrt(tt / STEP)));
+    return int(CGAL::to_double(CGAL::approximate_sqrt(tt / STEP)));
   }
 
   // s0 and s1 define a desired drawing "range"