diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 7dc93aa004c86cfa988993d53164ea1d665aff97..312ffd3d00177ca5a5e21393377c760e9bdec91e 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -173,7 +173,7 @@ static void unmap_switcher(void)
 bool lguest_address_ok(const struct lguest *lg,
 		       unsigned long addr, unsigned long len)
 {
-	return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
+	return addr+len <= lg->pfn_limit * PAGE_SIZE && (addr+len >= addr);
 }
 
 /*