diff --git a/arch/powerpc/sysdev/ipic.c b/arch/powerpc/sysdev/ipic.c
index 7367d17..95da897 100644
--- a/arch/powerpc/sysdev/ipic.c
+++ b/arch/powerpc/sysdev/ipic.c
@@ -736,7 +736,7 @@
 		return NULL;
 	}
 
-	ipic->regs = ioremap(res.start, res.end - res.start + 1);
+	ipic->regs = ioremap(res.start, resource_size(&res));
 
 	ipic->irqhost->host_data = ipic;