diff --git a/AABB_tree/include/CGAL/AABB_tree.h b/AABB_tree/include/CGAL/AABB_tree.h
index be0e6a9edb1..17abfa64757 100644
--- a/AABB_tree/include/CGAL/AABB_tree.h
+++ b/AABB_tree/include/CGAL/AABB_tree.h
@@ -580,7 +580,7 @@ public:
     {
       if (empty() && other_tree.empty())
       {
-        break
+        return;
       }
       else if (size() > 1 && other_tree.size() > 1)
       {