diff --git a/.github/workflows/upstream_install.sh b/.github/workflows/upstream_install.sh
index 28e0c73..f9dec5c 100755
--- a/.github/workflows/upstream_install.sh
+++ b/.github/workflows/upstream_install.sh
@@ -20,7 +20,10 @@ install_cloudsmith_repo() {
 }
 
 source /etc/os-release
-install_cloudsmith_repo machinekit machinekit-hal D35981AB4276AC36
+# FIXME Machinekit repos currently broken; use Zultron's "stable" repo
+# install_cloudsmith_repo machinekit machinekit-hal D35981AB4276AC36
+install_cloudsmith_repo zultron machinekit EB6FA9FCFA405632
+# Support packages
 install_cloudsmith_repo machinekit machinekit A9B6D8B4BD8321F3
 apt-get update