diff --git a/env/rhel7/x86_64/admin/stable/spack.yaml b/env/rhel7/x86_64/admin/stable/spack.yaml
index bbdc610..4648c5f 100644
--- a/env/rhel7/x86_64/admin/stable/spack.yaml
+++ b/env/rhel7/x86_64/admin/stable/spack.yaml
@@ -13,6 +13,6 @@ spack:
     - $spack/spack-psi/env/$os/$target_family/sysconfigs/compilers.yaml
   mirrors:
     local_stable: file:///afs/psi.ch/software/spack/stable
-    local_unstable: file:///afs/psi.ch/software/spack/unstable
-  specs: []
+  specs:
+    - gcc@12.3.0
   view: false
diff --git a/env/rhel7/x86_64/admin/testing/spack.yaml b/env/rhel7/x86_64/admin/testing/spack.yaml
index 911c146..6dc23ee 100644
--- a/env/rhel7/x86_64/admin/testing/spack.yaml
+++ b/env/rhel7/x86_64/admin/testing/spack.yaml
@@ -8,17 +8,12 @@ spack:
       - $spack/user/$user/spack-stage
     install_tree:
       root: $spack/opt/spack/testing
-  upstreams:
-    spack-instance-1:
-      install_tree: $spack/opt/spack/stable
-    spack-instance-2:
-      install_tree: $spack/opt/spack/unstable
   include:
     - $spack/spack-psi/env/$os/$target_family/sysconfigs/packages.yaml
     - $spack/spack-psi/env/$os/$target_family/sysconfigs/compilers.yaml
   mirrors:
-    local_unstable: file:///afs/psi.ch/software/spack/unstable
     local_testing: file:///afs/psi.ch/software/spack/testing
+    local_unstable: file:///afs/psi.ch/software/spack/unstable
   specs:
     - gcc@12.3.0
   view: false
diff --git a/env/rhel7/x86_64/admin/unstable/spack.yaml b/env/rhel7/x86_64/admin/unstable/spack.yaml
index 2fe5d67..85abf5a 100644
--- a/env/rhel7/x86_64/admin/unstable/spack.yaml
+++ b/env/rhel7/x86_64/admin/unstable/spack.yaml
@@ -8,16 +8,12 @@ spack:
       - $spack/user/$user/spack-stage
     install_tree:
       root: $spack/opt/spack/unstable
-  upstreams:
-    spack-instance-1:
-      install_tree: $spack/opt/spack/stable
   include:
     - $spack/spack-psi/env/$os/$target_family/sysconfigs/packages.yaml
     - $spack/spack-psi/env/$os/$target_family/sysconfigs/compilers.yaml
   mirrors:
-    local_stable: file:///afs/psi.ch/software/spack/stable
     local_unstable: file:///afs/psi.ch/software/spack/unstable
-    local_testing: file:///afs/psi.ch/software/spack/testing
+    local_stable: file:///afs/psi.ch/software/spack/stable
   specs:
     - gcc@12.3.0
   view: false