diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index c34cf5b73a..196a9f7200 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -848,6 +848,10 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed,
         bool int_req = relative_frame_number == frame_count &&
                        OHCI_BM(iso_td.flags, TD_DI) == 0;
         dev = ohci_find_device(ohci, OHCI_BM(ed->flags, ED_FA));
+        if (dev == NULL) {
+            trace_usb_ohci_td_dev_error();
+            return 1;
+        }
         ep = usb_ep_get(dev, pid, OHCI_BM(ed->flags, ED_EN));
         usb_packet_setup(&ohci->usb_packet, pid, ep, 0, addr, false, int_req);
         usb_packet_addbuf(&ohci->usb_packet, ohci->usb_buf, len);
@@ -1071,6 +1075,10 @@ static int ohci_service_td(OHCIState *ohci, struct ohci_ed *ed)
             return 1;
         }
         dev = ohci_find_device(ohci, OHCI_BM(ed->flags, ED_FA));
+        if (dev == NULL) {
+            trace_usb_ohci_td_dev_error();
+            return 1;
+        }
         ep = usb_ep_get(dev, pid, OHCI_BM(ed->flags, ED_EN));
         usb_packet_setup(&ohci->usb_packet, pid, ep, 0, addr, !flag_r,
                          OHCI_BM(td.flags, TD_DI) == 0);