diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c
index 563558d920..ad3d17f0fd 100644
--- a/src/conf/domain_validate.c
+++ b/src/conf/domain_validate.c
@@ -1260,6 +1260,17 @@ virDomainControllerDefValidate(const virDomainControllerDef *controller)
         }
     }
 
+    if (controller->iothread != 0) {
+        if (controller->type != VIR_DOMAIN_CONTROLLER_TYPE_SCSI ||
+            !(controller->model == VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_SCSI ||
+              controller->model == VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_TRANSITIONAL ||
+              controller->model == VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_NON_TRANSITIONAL)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("iothreads are supported only by 'virtio-scsi' controllers"));
+            return -1;
+        }
+    }
+
     return 0;
 }
 
diff --git a/tests/qemuxmlconfdata/controller-virtio-serial-iothread.x86_64-latest.err b/tests/qemuxmlconfdata/controller-virtio-serial-iothread.x86_64-latest.err
new file mode 100644
index 0000000000..ac4d8b2370
--- /dev/null
+++ b/tests/qemuxmlconfdata/controller-virtio-serial-iothread.x86_64-latest.err
@@ -0,0 +1 @@
+XML error: 'iothread' attribute only supported for virtio scsi controllers
diff --git a/tests/qemuxmlconfdata/controller-virtio-serial-iothread.xml b/tests/qemuxmlconfdata/controller-virtio-serial-iothread.xml
new file mode 100644
index 0000000000..0b523093c7
--- /dev/null
+++ b/tests/qemuxmlconfdata/controller-virtio-serial-iothread.xml
@@ -0,0 +1,27 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static' cpuset='1-4,8-20,525'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='virtio-serial' index='0'>
+      <driver iothread='3'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+    </controller>
+    <console type='pty'>
+      <target type='virtio'/>
+    </console>
+  </devices>
+</domain>
diff --git a/tests/qemuxmlconftest.c b/tests/qemuxmlconftest.c
index c271170d25..905b283f94 100644
--- a/tests/qemuxmlconftest.c
+++ b/tests/qemuxmlconftest.c
@@ -2824,6 +2824,8 @@ mymain(void)
     DO_TEST_CAPS_LATEST("virtio-options-rng-packed");
     DO_TEST_CAPS_LATEST("virtio-options-video-packed");
 
+    DO_TEST_CAPS_LATEST_PARSE_ERROR("controller-virtio-serial-iothread");
+
     DO_TEST_CAPS_LATEST("fd-memory-numa-topology");
     DO_TEST_CAPS_LATEST("fd-memory-numa-topology2");
     DO_TEST_CAPS_LATEST("fd-memory-numa-topology3");