diff --git a/board/common/qemu/ddi/run.sh b/board/common/qemu/ddi/run.sh
index 4f57ae7d8e..1128e2764c 100755
--- a/board/common/qemu/ddi/run.sh
+++ b/board/common/qemu/ddi/run.sh
@@ -140,7 +140,11 @@ q_add_disk()
 q_sect_device_usb()
 {
     if [ -z "$usb_bus_added" ]; then
-	q sect usb
+	case "$IX_QEMU_MACHINE" in
+	    q35*|pc*)
+		q sect device piix3-usb-uhci
+		;;
+	esac
 	q sect device usb-ehci
 	q param id ehci
 	usb_bus_added=YES
diff --git a/src/yangerd/internal/collector/ntp.go b/src/yangerd/internal/collector/ntp.go
index 75ea8dd230..7492403b91 100644
--- a/src/yangerd/internal/collector/ntp.go
+++ b/src/yangerd/internal/collector/ntp.go
@@ -245,8 +245,7 @@ func addAssociations(ntp map[string]interface{}, srcs []ntpSource) {
 	for _, src := range srcs {
 		d := src.data
 
-		// Skip reference clocks — they have refids, not addresses
-		if d.Mode == chrony.SourceModeRef {
+		if !resolved(d) {
 			continue
 		}
 
@@ -320,6 +319,16 @@ var sourceModeMap = map[chrony.ModeType]string{
 	chrony.SourceModeRef:    "local-clock",
 }
 
+// resolved reports whether a chrony source has an IP address: refclocks
+// carry a refid instead, and a server named by hostname has only a
+// placeholder ID until DNS answers.
+func resolved(d *chrony.ReplySourceData) bool {
+	if d.Mode == chrony.SourceModeRef || d.IPAddr == nil {
+		return false
+	}
+	return d.IPAddr.Family == chrony.IPAddrInet4 || d.IPAddr.Family == chrony.IPAddrInet6
+}
+
 // addSources builds the infix-system:ntp/sources/source list.
 // Reference clocks and sources with invalid stratum are skipped,
 // matching the Python yanger ietf_system.py add_ntp() behaviour.
@@ -328,7 +337,7 @@ func addSources(srcs []ntpSource) map[string]interface{} {
 	for _, src := range srcs {
 		d := src.data
 
-		if d.Mode == chrony.SourceModeRef {
+		if !resolved(d) {
 			continue
 		}
 		if d.Stratum > 16 {
diff --git a/src/yangerd/internal/collector/ntp_test.go b/src/yangerd/internal/collector/ntp_test.go
index b4f479fdf9..1cf839330e 100644
--- a/src/yangerd/internal/collector/ntp_test.go
+++ b/src/yangerd/internal/collector/ntp_test.go
@@ -155,6 +155,16 @@ func fullFakeChrony() *fakeChrony {
 	}
 }
 
+// unresolvedSource is a server configured by hostname that chronyd has
+// not resolved yet; cmdmon reports it with an ID placeholder address.
+func unresolvedSource() *chrony.ReplySourceData {
+	d := sourceData(nil, chrony.SourceModeClient, chrony.SourceStateUnreach,
+		0, 6, 0, 0, 0, 0)
+	d.IPAddr.Family = chrony.IPAddrID
+	d.IPAddr.IP[3] = 1
+	return d
+}
+
 func unsyncFakeChrony() *fakeChrony {
 	return &fakeChrony{
 		tracking: &chrony.ReplyTracking{
@@ -398,6 +408,26 @@ func ntpSourceCount(t *testing.T, tr *tree.Tree) int {
 	return len(ntp.Sources.Source)
 }
 
+func TestNTPUnresolvedSourceSkipped(t *testing.T) {
+	fake := fullFakeChrony()
+	fake.data = append(fake.data, unresolvedSource())
+	fake.stats = append(fake.stats, nil)
+
+	out, tr := ntpCollect(t, fake)
+	assocs := out["associations"].(map[string]interface{})["association"].([]interface{})
+	if len(assocs) != 3 {
+		t.Fatalf("expected 3 associations, got %d", len(assocs))
+	}
+	for _, a := range assocs {
+		if addr := a.(map[string]interface{})["address"].(string); addr == "ID#0000000001" {
+			t.Fatal("unresolved source leaked into associations")
+		}
+	}
+	if n := ntpSourceCount(t, tr); n != 4 {
+		t.Fatalf("expected 4 NTP sources, got %d", n)
+	}
+}
+
 func TestNTPSourcesEmpty(t *testing.T) {
 	fake := &fakeChrony{tracking: fullFakeChrony().tracking}
 
diff --git a/test/templates/inc/infix-usb.mustache b/test/templates/inc/infix-usb.mustache
index 9dabb2ca17..e7f4aa8544 100644
--- a/test/templates/inc/infix-usb.mustache
+++ b/test/templates/inc/infix-usb.mustache
@@ -5,5 +5,5 @@ if [ -n "{{qn_usb}}" ]; then
        dd if=/dev/zero of={{qn_usb}} bs=8M count=1 >/dev/null 2>&1
        mkfs.vfat {{qn_usb}}  >/dev/null 2>&1
    fi
-   usb_cmd=" -drive if=none,id=usbstick,format=raw,file={{qn_usb}} -usb -device usb-ehci,id=ehci -device usb-storage,bus=ehci.0,drive=usbstick "
+   usb_cmd=" -drive if=none,id=usbstick,format=raw,file={{qn_usb}} -device piix3-usb-uhci,id=uhci -device usb-ehci,id=ehci -device usb-storage,bus=ehci.0,drive=usbstick "
 fi