diff --git a/.gitmodules b/.gitmodules
index b33ca86e0..04514feb5 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,8 +1,8 @@
 [submodule "spack"]
   path = spack
   url = https://github.com/jcsda/spack
-  branch = release/2.1
+  branch = spack-stack-2.1.0
 [submodule "repos/builtin"]
   path = repos/builtin
   url = https://github.com/jcsda/spack-packages
-  branch = release/2.1
+  branch = spack-stack-2.1.0
diff --git a/repos/builtin b/repos/builtin
index 340a3da5d..4a3312cc2 160000
--- a/repos/builtin
+++ b/repos/builtin
@@ -1 +1 @@
-Subproject commit 340a3da5d2471874648e2cc7e623f8da420265db
+Subproject commit 4a3312cc241c0da954ab450cbdd223122a62355f