diff --git a/Approximate_min_ellipsoid_d/include/CGAL/Approximate_min_ellipsoid_d/Approximate_min_ellipsoid_d_debug.h b/Approximate_min_ellipsoid_d/include/CGAL/Approximate_min_ellipsoid_d/Approximate_min_ellipsoid_d_debug.h
index e87fd456538..092769a7ab4 100644
--- a/Approximate_min_ellipsoid_d/include/CGAL/Approximate_min_ellipsoid_d/Approximate_min_ellipsoid_d_debug.h
+++ b/Approximate_min_ellipsoid_d/include/CGAL/Approximate_min_ellipsoid_d/Approximate_min_ellipsoid_d_debug.h
@@ -24,6 +24,7 @@
 #include <map>
 #include <iostream>
 #include <fstream>
+#include <sstream>
 
 namespace CGAL {