diff --git a/arch_init.c b/arch_init.c
index 68a7ab7..ac8eb59 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -342,7 +342,8 @@
 {
     unsigned long base = mr->ram_addr >> TARGET_PAGE_BITS;
     unsigned long nr = base + (start >> TARGET_PAGE_BITS);
-    unsigned long size = base + (int128_get64(mr->size) >> TARGET_PAGE_BITS);
+    uint64_t mr_size = TARGET_PAGE_ALIGN(memory_region_size(mr));
+    unsigned long size = base + (mr_size >> TARGET_PAGE_BITS);
 
     unsigned long next;