diff --git a/json_object.h b/json_object.h
index 1ee9fb0..e9898f4 100644
--- a/json_object.h
+++ b/json_object.h
@@ -79,6 +79,7 @@
  * Check if the json_object is of a given type
  * @param obj the json_object instance
  * @param type one of:
+     json_type_null (i.e. obj == NULL),
      json_type_boolean,
      json_type_double,
      json_type_int,
@@ -92,6 +93,7 @@
  * Get the type of the json_object
  * @param obj the json_object instance
  * @returns type being one of:
+     json_type_null (i.e. obj == NULL),
      json_type_boolean,
      json_type_double,
      json_type_int,