diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index 7dc87fc7bd..c7a64e6b8d 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -282,8 +282,7 @@ void spapr_dt_events(sPAPRMachineState *spapr, void *fdt)
             continue;
         }
 
-        interrupts[0] = cpu_to_be32(source->irq);
-        interrupts[1] = 0;
+        spapr_dt_xics_irq(interrupts, source->irq, false);
 
         _FDT(node_offset = fdt_add_subnode(fdt, event_sources, source_name));
         _FDT(fdt_setprop(fdt, node_offset, "interrupts", interrupts,
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 39134f0ef0..88797b3d36 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -2121,8 +2121,7 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
             irqmap[2] = 0;
             irqmap[3] = cpu_to_be32(j+1);
             irqmap[4] = cpu_to_be32(xics_phandle);
-            irqmap[5] = cpu_to_be32(phb->lsi_table[lsi_num].irq);
-            irqmap[6] = cpu_to_be32(0x8);
+            spapr_dt_xics_irq(&irqmap[5], phb->lsi_table[lsi_num].irq, true);
         }
     }
     /* Write interrupt map */
diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
index bb7ed2c537..472dd6f33a 100644
--- a/hw/ppc/spapr_vio.c
+++ b/hw/ppc/spapr_vio.c
@@ -126,8 +126,9 @@ static int vio_make_devnode(VIOsPAPRDevice *dev,
     }
 
     if (dev->irq) {
-        uint32_t ints_prop[] = {cpu_to_be32(dev->irq), 0};
+        uint32_t ints_prop[2];
 
+        spapr_dt_xics_irq(ints_prop, dev->irq, false);
         ret = fdt_setprop(fdt, node_off, "interrupts", ints_prop,
                           sizeof(ints_prop));
         if (ret < 0) {
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 6b8e04c787..14757b805e 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -590,6 +590,16 @@ void spapr_load_rtas(sPAPRMachineState *spapr, void *fdt, hwaddr addr);
 
 #define RTAS_EVENT_SCAN_RATE    1
 
+/* This helper should be used to encode interrupt specifiers when the related
+ * "interrupt-controller" node has its "#interrupt-cells" property set to 2 (ie,
+ * VIO devices, RTAS event sources and PHBs).
+ */
+static inline void spapr_dt_xics_irq(uint32_t *intspec, int irq, bool is_lsi)
+{
+    intspec[0] = cpu_to_be32(irq);
+    intspec[1] = is_lsi ? cpu_to_be32(1) : 0;
+}
+
 typedef struct sPAPRTCETable sPAPRTCETable;
 
 #define TYPE_SPAPR_TCE_TABLE "spapr-tce-table"