diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index 93f0ddc..bbdac4a 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -495,6 +495,10 @@ function node_type_load($name) {
 /**
  * Saves a node type to the database.
  *
+ * If you are manually modifying a node type ensure that you set the modified
+ * property to TRUE otherwise the changes will be stored in the database, but
+ * ignored by the API.
+ *
  * @param $info
  *   The node type to save, as an object.
  *