diff --git a/runtime/gc.c b/runtime/gc.c
index cbbc7e730..75ef2675e 100644
--- a/runtime/gc.c
+++ b/runtime/gc.c
@@ -26,7 +26,8 @@ static extra_roots_pool extra_roots;
 
 size_t __gc_stack_top = 0, __gc_stack_bottom = 0;
 #ifdef LAMA_ENV
-extern const size_t __start_custom_data, __stop_custom_data;
+extern const size_t __start_custom_data __asm("section$start$__DATA$custom_data");
+extern const size_t __stop_custom_data __asm("section$end$__DATA$custom_data");
 #endif
 
 #ifdef DEBUG_VERSION