diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index b9db8e529e4d..dbbe3932f833 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -604,7 +604,7 @@ void __init mem_init(void)
 			> BITS_PER_LONG);
 
 	high_memory = __va((max_pfn << PAGE_SHIFT));
-	set_max_mapnr(page_to_pfn(virt_to_page(high_memory - 1)) + 1);
+	set_max_mapnr(max_low_pfn);
 	free_all_bootmem();
 
 #ifdef CONFIG_PA11