diff --git a/hw/ppc/mac_newworld.c b/hw/ppc/mac_newworld.c
index 66d016c6fa..1b9a573cae 100644
--- a/hw/ppc/mac_newworld.c
+++ b/hw/ppc/mac_newworld.c
@@ -371,12 +371,13 @@ static void ppc_core99_init(MachineState *machine)
         /* 970 gets a U3 bus */
         pci_bus = pci_pmac_u3_init(pic, get_system_memory(), get_system_io());
         machine_arch = ARCH_MAC99_U3;
-        machine->usb |= defaults_enabled() && !machine->usb_disabled;
     } else {
         pci_bus = pci_pmac_init(pic, get_system_memory(), get_system_io());
         machine_arch = ARCH_MAC99;
     }
 
+    machine->usb |= defaults_enabled() && !machine->usb_disabled;
+
     /* Timebase Frequency */
     if (kvm_enabled()) {
         tbfreq = kvmppc_get_tbfreq();