diff --git a/tools/buildman/README b/tools/buildman/README
index f299b0c..0663ec3 100644
--- a/tools/buildman/README
+++ b/tools/buildman/README
@@ -1124,6 +1124,9 @@
 
 If there are both warnings and errors, errors win, so buildman returns 128.
 
+The -y option is provided (for use with -s) to ignore the bountiful device-tree
+warnings.
+
 
 How to change from MAKEALL
 ==========================