diff --git a/tools/buildman/README b/tools/buildman/README
index d4e8404..d20508f 100644
--- a/tools/buildman/README
+++ b/tools/buildman/README
@@ -690,6 +690,12 @@
 
 Buildman has various other command line options. Try --help to see them.
 
+When doing builds, Buildman's return code will reflect the overall result:
+
+    0 (success)     No errors or warnings found
+    128             Errors found
+    129             Warnings found
+
 
 How to change from MAKEALL
 ==========================