diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 5d38c47444..77d9267599 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -923,7 +923,7 @@ static void machvirt_init(MachineState *machine)
     qemu_irq pic[NUM_IRQS];
     MemoryRegion *sysmem = get_system_memory();
     int gic_version = vms->gic_version;
-    int n;
+    int n, max_cpus;
     MemoryRegion *ram = g_new(MemoryRegion, 1);
     const char *cpu_model = machine->cpu_model;
     VirtBoardInfo *vbi;
@@ -957,6 +957,22 @@ static void machvirt_init(MachineState *machine)
         exit(1);
     }
 
+    /* The maximum number of CPUs depends on the GIC version, or on how
+     * many redistributors we can fit into the memory map.
+     */
+    if (gic_version == 3) {
+        max_cpus = vbi->memmap[VIRT_GIC_REDIST].size / 0x20000;
+    } else {
+        max_cpus = GIC_NCPU;
+    }
+
+    if (smp_cpus > max_cpus) {
+        error_report("Number of SMP CPUs requested (%d) exceeds max CPUs "
+                     "supported by machine 'mach-virt' (%d)",
+                     smp_cpus, max_cpus);
+        exit(1);
+    }
+
     vbi->smp_cpus = smp_cpus;
 
     if (machine->ram_size > vbi->memmap[VIRT_MEM].size) {
@@ -1155,10 +1171,11 @@ static void virt_class_init(ObjectClass *oc, void *data)
 
     mc->desc = "ARM Virtual Machine",
     mc->init = machvirt_init;
-    /* Our maximum number of CPUs depends on how many redistributors
-     * we can fit into memory map
+    /* Start max_cpus at the maximum QEMU supports. We'll further restrict
+     * it later in machvirt_init, where we have more information about the
+     * configuration of the particular instance.
      */
-    mc->max_cpus = a15memmap[VIRT_GIC_REDIST].size / 0x20000;
+    mc->max_cpus = MAX_CPUMASK_BITS;
     mc->has_dynamic_sysbus = true;
     mc->block_default_type = IF_VIRTIO;
     mc->no_cdrom = 1;