diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 906f29c..bfc6211 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1376,7 +1376,7 @@
 	mpic->isu_mask = (1 << mpic->isu_shift) - 1;
 
 	mpic->irqhost = irq_domain_add_linear(mpic->node,
-				       last_irq + 1,
+				       intvec_top,
 				       &mpic_host_ops, mpic);
 
 	/*