diff --git a/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Arc_2.h b/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Arc_2.h
index 3080b586837..50380fc882e 100644
--- a/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Arc_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Arc_2.h
@@ -37,6 +37,8 @@
 
 #include <CGAL/Curved_kernel_via_analysis_2/Sweep_curves_adapter_2.h>
 
+#include <CGAL/kernel_assertions.h>
+
 namespace CGAL {
 
 namespace internal {
diff --git a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/assertions.h b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/assertions.h
index 6d282c45d6a..3916c7627c5 100644
--- a/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/assertions.h
+++ b/Straight_skeleton_2/include/CGAL/Straight_skeleton_2/assertions.h
@@ -13,6 +13,7 @@
 
 #include <CGAL/license/Straight_skeleton_2.h>
 
+#include <CGAL/assertions.h>
 
 #if defined(CGAL_STRAIGHT_SKELETON_NO_POSTCONDITIONS) \
   || defined(CGAL_NO_POSTCONDITIONS) \