# Overriding tree builder args **URL:** \ **Category:** Help and Getting Started\ **Created:** [March 24, 2022, 8:59pm UTC](https://nextstrain.discourse.group/t/overriding-tree-builder-args/1051 "2022-03-24T20:59:50Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![GVeytsel](https://avatars.discourse-cdn.com/v4/letter/g/5f9b8f/32.png) [@GVeytsel](https://nextstrain.discourse.group/u/GVeytsel)\ **Post date:** [March 24, 2022, 8:59pm UTC](https://nextstrain.discourse.group/t/overriding-tree-builder-args/1051/1 "2022-03-24T20:59:50Z")
Hello, I was hoping to add bootstrap support to the ml tree, but I haven’t been able to override the default argument of ninit 10 -n 4 which conflicts with the bootstrap argument. I haven’t been able to find much documentation on this option, but my latest attempt is to add the below text to builds.yaml: tree: override-default-args: “true” tree-builder-args: “’-bb 100’” But I still get the error below: ![Capture](https://canada1.discourse-cdn.com/flex031/uploads/nextstrain/original/1X/c82d2fb6cb6e921938aee5a1709c4a88ebcd4b28.png) Thanks for any help! ---
**Author:** ![joverlee](https://avatars.discourse-cdn.com/v4/letter/j/e495f1/32.png) [@joverlee](https://nextstrain.discourse.group/u/joverlee)\ **Post date:** [March 28, 2022, 8:03pm UTC](https://nextstrain.discourse.group/t/overriding-tree-builder-args/1051/2 "2022-03-28T20:03:17Z")
Hi @GVeytsel, The `override-default-args` parameter is not available in the ncov workflow just yet. There is an [open pull request](https://github.com/nextstrain/ncov/pull/871) for this feature. Best, Jover ---
**Author:** ![GVeytsel](https://avatars.discourse-cdn.com/v4/letter/g/5f9b8f/32.png) [@GVeytsel](https://nextstrain.discourse.group/u/GVeytsel)\ **Post date:** [March 28, 2022, 8:21pm UTC](https://nextstrain.discourse.group/t/overriding-tree-builder-args/1051/3 "2022-03-28T20:21:23Z")
Thank you so much for clarifying!