diff --git a/hw/cpu/a15mpcore.c b/hw/cpu/a15mpcore.c
index d24ab0a6ab..676f65a0af 100644
--- a/hw/cpu/a15mpcore.c
+++ b/hw/cpu/a15mpcore.c
@@ -58,6 +58,11 @@ static void a15mp_priv_realize(DeviceState *dev, Error **errp)
     bool has_el2 = false;
     Object *cpuobj;
 
+    if (s->num_irq < 32 || s->num_irq > 256) {
+        error_setg(errp, "Property 'num-irq' must be between 32 and 256");
+        return;
+    }
+
     gicdev = DEVICE(&s->gic);
     qdev_prop_set_uint32(gicdev, "num-cpu", s->num_cpu);
     qdev_prop_set_uint32(gicdev, "num-irq", s->num_irq);
@@ -146,13 +151,14 @@ static void a15mp_priv_realize(DeviceState *dev, Error **errp)
 
 static const Property a15mp_priv_properties[] = {
     DEFINE_PROP_UINT32("num-cpu", A15MPPrivState, num_cpu, 1),
-    /* The Cortex-A15MP may have anything from 0 to 224 external interrupt
-     * IRQ lines (with another 32 internal). We default to 128+32, which
-     * is the number provided by the Cortex-A15MP test chip in the
-     * Versatile Express A15 development board.
-     * Other boards may differ and should set this property appropriately.
+    /*
+     * The Cortex-A15MP may have anything from 0 to 224 external interrupt
+     * lines, plus always 32 internal IRQs. This property sets the total
+     * of internal + external, so the valid range is from 32 to 256.
+     * The board model must set this to whatever the configuration
+     * used for the CPU on that board or SoC is.
      */
-    DEFINE_PROP_UINT32("num-irq", A15MPPrivState, num_irq, 160),
+    DEFINE_PROP_UINT32("num-irq", A15MPPrivState, num_irq, 0),
 };
 
 static void a15mp_priv_class_init(ObjectClass *klass, void *data)
diff --git a/hw/cpu/a9mpcore.c b/hw/cpu/a9mpcore.c
index 25416c5032..1b9f2bef93 100644
--- a/hw/cpu/a9mpcore.c
+++ b/hw/cpu/a9mpcore.c
@@ -56,6 +56,11 @@ static void a9mp_priv_realize(DeviceState *dev, Error **errp)
     CPUState *cpu0;
     Object *cpuobj;
 
+    if (s->num_irq < 32 || s->num_irq > 256) {
+        error_setg(errp, "Property 'num-irq' must be between 32 and 256");
+        return;
+    }
+
     cpu0 = qemu_get_cpu(0);
     cpuobj = OBJECT(cpu0);
     if (strcmp(object_get_typename(cpuobj), ARM_CPU_TYPE_NAME("cortex-a9"))) {
@@ -160,13 +165,14 @@ static void a9mp_priv_realize(DeviceState *dev, Error **errp)
 
 static const Property a9mp_priv_properties[] = {
     DEFINE_PROP_UINT32("num-cpu", A9MPPrivState, num_cpu, 1),
-    /* The Cortex-A9MP may have anything from 0 to 224 external interrupt
-     * IRQ lines (with another 32 internal). We default to 64+32, which
-     * is the number provided by the Cortex-A9MP test chip in the
-     * Realview PBX-A9 and Versatile Express A9 development boards.
-     * Other boards may differ and should set this property appropriately.
+    /*
+     * The Cortex-A9MP may have anything from 0 to 224 external interrupt
+     * lines, plus always 32 internal IRQs. This property sets the total
+     * of internal + external, so the valid range is from 32 to 256.
+     * The board model must set this to whatever the configuration
+     * used for the CPU on that board or SoC is.
      */
-    DEFINE_PROP_UINT32("num-irq", A9MPPrivState, num_irq, 96),
+    DEFINE_PROP_UINT32("num-irq", A9MPPrivState, num_irq, 0),
 };
 
 static void a9mp_priv_class_init(ObjectClass *klass, void *data)