diff --git a/libcxx/modules/std.compat/cstdlib.inc b/libcxx/modules/std.compat/cstdlib.inc
index a45a0a1caf8ba..4783cbf516239 100644
--- a/libcxx/modules/std.compat/cstdlib.inc
+++ b/libcxx/modules/std.compat/cstdlib.inc
@@ -25,7 +25,7 @@ export {
   using ::system;
 
   // [c.malloc], C library memory allocation
-  using ::aligned_alloc;
+  using ::aligned_alloc _LIBCPP_USING_IF_EXISTS;
   using ::calloc;
   using ::free;
   using ::malloc;