diff --git a/doc/test-runner.txt b/doc/test-runner.txt
index 3fa236f9..53f56691 100644
--- a/doc/test-runner.txt
+++ b/doc/test-runner.txt
@@ -197,6 +197,11 @@ radio_confs=rad0:rad1
 # This field is optional. Default: 1 (true)
 #start_iwd=0
 
+# Configuration directory to use for IWD daemon. IWD expects 'iwd.conf' to be
+# inside of the specified directory.
+# This field is optional. Default: /etc/iwd
+#iwd_config_dir=/etc/iwd
+
 #
 # The following two configuration groups are examples of the radio
 # configurations.