diff --git a/CGAL_Core/include/CGAL/CORE/BigInt.h b/CGAL_Core/include/CGAL/CORE/BigInt.h
index fff3c91eef72..20e216cf5402 100644
--- a/CGAL_Core/include/CGAL/CORE/BigInt.h
+++ b/CGAL_Core/include/CGAL/CORE/BigInt.h
@@ -30,7 +30,7 @@
 #include <string>
 
 
-#if !(BOOST_VERSION > 107900 && defined(CGAL_USE_BOOST_MP))
+#if !(defined(CGAL_CORE_USE_BOOST_BACKEND) && BOOST_VERSION > 107900 && defined(CGAL_USE_BOOST_MP))
 #define CGAL_CORE_USE_GMP_BACKEND 1
 #endif