diff --git a/doc/api/child_process.md b/doc/api/child_process.md
index a01b0db9b25a8f..33027468eaf543 100644
--- a/doc/api/child_process.md
+++ b/doc/api/child_process.md
@@ -263,6 +263,8 @@ added: v0.5.0
     [`stdio`][] for more details (Default: `false`)
   * `stdio` {Array} Supports the array version of [`child_process.spawn()`][]'s
     [`stdio`][] option. When this option is provided, it overrides `silent`.
+    The array must contain exactly one item with value `'ipc'` or an error will
+    be thrown. For instance `[0, 1, 2, 'ipc']`.
   * `uid` {Number} Sets the user identity of the process. (See setuid(2).)
   * `gid` {Number} Sets the group identity of the process. (See setgid(2).)
 * Return: {ChildProcess}