diff --git a/.buildkite/hooks/post-checkout b/.buildkite/hooks/post-checkout
index 786f8c78e..8714ab2ab 100755
--- a/.buildkite/hooks/post-checkout
+++ b/.buildkite/hooks/post-checkout
@@ -5,7 +5,7 @@ set -euo pipefail
 # Buildkite users can trigger new builds with these values overridden to
 # test specific julia gitshas
 UPSTREAM_URL="${UPSTREAM_URL:-https://github.com/JuliaLang/julia.git}"
-UPSTREAM_BRANCH="${UPSTREAM_BRANCH:-master}"
+UPSTREAM_BRANCH="${UPSTREAM_BRANCH:-sf/macos_pkg_fixes}"
 
 # All of our workers are required to provide a default for the julia cache dir
 # We're going to cache repositories in here, just like buildkite itself would: