diff --git a/hw/usb/core.c b/hw/usb/core.c
index 01a7622837..c7e5bc047f 100644
--- a/hw/usb/core.c
+++ b/hw/usb/core.c
@@ -107,6 +107,7 @@ static int do_token_setup(USBDevice *s, USBPacket *p)
     }
 
     usb_packet_copy(p, s->setup_buf, p->iov.size);
+    p->result = 0;
     s->setup_len   = (s->setup_buf[7] << 8) | s->setup_buf[6];
     s->setup_index = 0;
 
diff --git a/hw/usb/host-linux.c b/hw/usb/host-linux.c
index d55be878ad..8df92074d3 100644
--- a/hw/usb/host-linux.c
+++ b/hw/usb/host-linux.c
@@ -1045,6 +1045,7 @@ static int usb_host_handle_control(USBDevice *dev, USBPacket *p,
 
     /* Note request is (bRequestType << 8) | bRequest */
     trace_usb_host_req_control(s->bus_num, s->addr, p, request, value, index);
+    assert(p->result == 0);
 
     switch (request) {
     case DeviceOutRequest | USB_REQ_SET_ADDRESS: