diff --git a/hw/spapr.c b/hw/spapr.c
index 64c35a8..789c941 100644
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -798,7 +798,7 @@ static void ppc_spapr_init(ram_addr_t ram_size,
 
     /* Set up Interrupt Controller */
     spapr->icp = xics_system_init(XICS_IRQS);
-    spapr->next_irq = 16;
+    spapr->next_irq = XICS_IRQ_BASE;
 
     /* Set up EPOW events infrastructure */
     spapr_events_init(spapr);
diff --git a/hw/xics.c b/hw/xics.c
index 7a899dd..db01fe3 100644
--- a/hw/xics.c
+++ b/hw/xics.c
@@ -548,7 +548,7 @@ struct icp_state *xics_system_init(int nr_irqs)
 
     ics = g_malloc0(sizeof(*ics));
     ics->nr_irqs = nr_irqs;
-    ics->offset = 16;
+    ics->offset = XICS_IRQ_BASE;
     ics->irqs = g_malloc0(nr_irqs * sizeof(struct ics_irq_state));
 
     icp->ics = ics;
diff --git a/hw/xics.h b/hw/xics.h
index 6817268..c3bf008 100644
--- a/hw/xics.h
+++ b/hw/xics.h
@@ -28,6 +28,7 @@
 #define __XICS_H__
 
 #define XICS_IPI        0x2
+#define XICS_IRQ_BASE   0x10
 
 struct icp_state;