diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index dff6d42cfca033298b42ad569a55bd914bfe9d9e..6802643bfd187d3e261e457c5a6736d22065785f 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -4618,15 +4618,19 @@ int qemuMonitorJSONSetBlockIoThrottle(qemuMonitorPtr mon,
         goto cleanup;
 
     if (virJSONValueObjectHasKey(result, "error")) {
-        if (qemuMonitorJSONHasError(result, "DeviceNotActive"))
+        if (qemuMonitorJSONHasError(result, "DeviceNotActive")) {
             virReportError(VIR_ERR_OPERATION_INVALID,
                            _("No active operation on device: %s"), device);
-        else if (qemuMonitorJSONHasError(result, "NotSupported"))
+        } else if (qemuMonitorJSONHasError(result, "NotSupported")) {
             virReportError(VIR_ERR_OPERATION_INVALID,
                            _("Operation is not supported for device: %s"), device);
-        else
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("Unexpected error"));
+        } else {
+            virJSONValuePtr error = virJSONValueObjectGet(result, "error");
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("unable to execute '%s', unexpected error: '%s'"),
+                           qemuMonitorJSONCommandName(cmd),
+                           qemuMonitorJSONStringifyError(error));
+        }
         goto cleanup;
     }