diff --git a/json.go b/json.go
index c1a210c16310b584a6b11398c2dc2c6c60d99f37..e58162265e42f2f8ed98141368652ed6d5019652 100644
--- a/json.go
+++ b/json.go
@@ -312,6 +312,8 @@ func parsePositionalArguments(rawArgs json.RawMessage, types []reflect.Type) ([]
 		if args, err = parseArgumentArray(rawArgs, types); err != nil {
 			return nil, err
 		}
+	case string(rawArgs) == "null":
+		return nil, nil
 	default:
 		return nil, errors.New("non-array args")
 	}