diff --git a/src/util/virjson.c b/src/util/virjson.c
index 6e13e97e15..ae970c7653 100644
--- a/src/util/virjson.c
+++ b/src/util/virjson.c
@@ -121,6 +121,7 @@ virJSONValueGetType(const virJSONValue *value)
  *
  * I: signed long integer value
  * J: signed long integer value, error if negative
+ * K: signed long integer value, omitted if negative
  * Z: signed long integer value, omitted if zero
  * Y: signed long integer value, omitted if zero, error if negative
  *
@@ -228,6 +229,7 @@ virJSONValueObjectAddVArgs(virJSONValue **objptr,
 
         case 'Z':
         case 'Y':
+        case 'K':
         case 'J':
         case 'I': {
             long long val = va_arg(args, long long);
@@ -242,6 +244,9 @@ virJSONValueObjectAddVArgs(virJSONValue **objptr,
             if (!val && (type == 'Z' || type == 'Y'))
                 continue;
 
+            if (val < 0 && type == 'K')
+                continue;
+
             rc = virJSONValueObjectAppendNumberLong(obj, key, val);
         }   break;