diff --git a/script/build/serprog b/script/build/serprog
index 28cd70a4..8b003add 100755
--- a/script/build/serprog
+++ b/script/build/serprog
@@ -71,7 +71,7 @@ print_boards()
 
 list_boards()
 {
-	basename -a -s .h "${1}/"*.h
+	basename -a -s .h "${1}/"*.h || err "list_boards $1: can't list boards"
 }
 
 main $@