diff --git a/arch/um/kernel/tt/mem.c b/arch/um/kernel/tt/mem.c
index 74346a0..bcb8796 100644
--- a/arch/um/kernel/tt/mem.c
+++ b/arch/um/kernel/tt/mem.c
@@ -21,14 +21,8 @@
 	remap_data(UML_ROUND_DOWN(&__bss_start), UML_ROUND_UP(&_end), 1);
 }
 
-#ifdef CONFIG_HOST_2G_2G
-#define TOP 0x80000000
-#else
-#define TOP 0xc0000000
-#endif
-
 #define SIZE ((CONFIG_NEST_LEVEL + CONFIG_KERNEL_HALF_GIGS) * 0x20000000)
-#define START (TOP - SIZE)
+#define START (CONFIG_TOP_ADDR - SIZE)
 
 unsigned long set_task_sizes_tt(int arg, unsigned long *host_size_out, 
 				unsigned long *task_size_out)