diff --git a/root.bp b/root.bp
index d91da6456..f27d28b68 100644
--- a/root.bp
+++ b/root.bp
@@ -37,5 +37,6 @@ optional_subdirs = [
     "test/vts",
     "test/vts-testcase/*",
     "tools/*",
+    "toolchain/*",
     "vendor/*/*",
 ]