diff --git a/build-support/factor.sh b/build-support/factor.sh
index 4bcd9e3086..70c522f6cd 100755
--- a/build-support/factor.sh
+++ b/build-support/factor.sh
@@ -439,7 +439,7 @@ install_build_system_port() {
 }
 
 usage() {
-    echo "usage: $0 install|install-x11|install-macosx|self-update|quick-update|update|bootstrap|net-bootstrap|make-target"
+    echo "usage: $0 install|install-x11|install-macosx|self-update|quick-update|update|bootstrap|dlls|net-bootstrap|make-target"
     echo "If you are behind a firewall, invoke as:"
     echo "env GIT_PROTOCOL=http $0 <command>"
 }