diff --git a/xen/arch/riscv/include/asm/mm.h b/xen/arch/riscv/include/asm/mm.h
index 2a8f9a1a44..5e3ac5cde3 100644
--- a/xen/arch/riscv/include/asm/mm.h
+++ b/xen/arch/riscv/include/asm/mm.h
@@ -8,6 +8,8 @@
 #define pfn_to_paddr(pfn) ((paddr_t)(pfn) << PAGE_SHIFT)
 #define paddr_to_pfn(pa)  ((unsigned long)((pa) >> PAGE_SHIFT))
 
+extern unsigned char cpu0_boot_stack[];
+
 void setup_initial_pagetables(void);
 
 void enable_mmu(void);
diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c
index 40b781a2fa..fddb3cd0bd 100644
--- a/xen/arch/riscv/mm.c
+++ b/xen/arch/riscv/mm.c
@@ -19,8 +19,6 @@ struct mmu_desc {
     pte_t *pgtbl_base;
 };
 
-extern unsigned char cpu0_boot_stack[STACK_SIZE];
-
 #define PHYS_OFFSET ((unsigned long)_start - XEN_VIRT_START)
 #define LOAD_TO_LINK(addr) ((addr) - PHYS_OFFSET)
 #define LINK_TO_LOAD(addr) ((addr) + PHYS_OFFSET)