diff --git a/src/util/virjson.c b/src/util/virjson.c
index 9adcea4fff..26491bd6c7 100644
--- a/src/util/virjson.c
+++ b/src/util/virjson.c
@@ -115,6 +115,7 @@ virJSONValueGetType(const virJSONValue *value)
  *
  * i: signed integer value
  * j: signed integer value, error if negative
+ * k: signed integer value, omitted if negative
  * z: signed integer value, omitted if zero
  * y: signed integer value, omitted if zero, error if negative
  *
@@ -189,6 +190,7 @@ virJSONValueObjectAddVArgs(virJSONValue *obj,
 
         case 'z':
         case 'y':
+        case 'k':
         case 'j':
         case 'i': {
             int val = va_arg(args, int);
@@ -203,6 +205,9 @@ virJSONValueObjectAddVArgs(virJSONValue *obj,
             if (!val && (type == 'z' || type == 'y'))
                 continue;
 
+            if (val < 0 && type == 'k')
+                continue;
+
             rc = virJSONValueObjectAppendNumberInt(obj, key, val);
         }   break;