diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 04ec69e4d02e..53afa14eb314 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -822,7 +822,7 @@ static void xen_alloc_ptpage(struct mm_struct *mm, u32 pfn, unsigned level)
 		SetPagePinned(page);
 
 		if (!PageHighMem(page)) {
-			make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
+			make_lowmem_page_readonly(__va(PFN_PHYS((unsigned long)pfn)));
 			if (level == PT_PTE)
 				pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
 		} else