diff --git a/Algebraic_kernel_d/include/CGAL/Algebraic_kernel_d/Curve_pair_analysis_2.h b/Algebraic_kernel_d/include/CGAL/Algebraic_kernel_d/Curve_pair_analysis_2.h
index 97b0c3f63d0..28e270f0fac 100644
--- a/Algebraic_kernel_d/include/CGAL/Algebraic_kernel_d/Curve_pair_analysis_2.h
+++ b/Algebraic_kernel_d/include/CGAL/Algebraic_kernel_d/Curve_pair_analysis_2.h
@@ -1435,7 +1435,13 @@ compute_event_x_coordinates_with_event_indices() const {
                 CGAL_ACK_DEBUG_PRINT << " one curve event" << std::endl;
 #endif
 */
+#if CGAL_CXX11
+            // Fix a warning by using `emplace_back()` instead of
+            // copying a non-initialized `optional
+            this->ptr()->event_slices.emplace_back();
+#else
             this->ptr()->event_slices.push_back(Lazy_status_line_CPA_1());
+#endif
             switch(*(one_curve_it++)) {
             case(CGAL::internal::ROOT_OF_FIRST_SET): {
                 event_indices.push_back(Event_indices(-1,f_count,-1));
@@ -1462,8 +1468,11 @@ compute_event_x_coordinates_with_event_indices() const {
             CGAL_ACK_DEBUG_PRINT << " two curve event" << std::endl;
 #endif
 */
-            this->ptr()->
-                event_slices.push_back(Lazy_status_line_CPA_1());
+#if CGAL_CXX11
+            this->ptr()->event_slices.emplace_back();
+#else
+            this->ptr()->event_slices.push_back(Lazy_status_line_CPA_1());
+#endif
             
             event_indices.push_back
                 (Event_indices(inter_count,-1,-1));
@@ -1477,7 +1486,11 @@ compute_event_x_coordinates_with_event_indices() const {
                                      << std::endl;
 #endif
 */
+#if CGAL_CXX11
+            this->ptr()->event_slices.emplace_back();
+#else
             this->ptr()->event_slices.push_back(Lazy_status_line_CPA_1());
+#endif
             
             
             switch(*(one_curve_it++)) {