diff --git a/share/spack/gitlab/cloud_pipelines/stacks/build_systems/spack.yaml b/share/spack/gitlab/cloud_pipelines/stacks/build_systems/spack.yaml
index eb60dd85fe1..4808763f374 100644
--- a/share/spack/gitlab/cloud_pipelines/stacks/build_systems/spack.yaml
+++ b/share/spack/gitlab/cloud_pipelines/stacks/build_systems/spack.yaml
@@ -3,7 +3,7 @@ spack:
 
   concretizer:
     reuse: false
-    unify: when_possible
+    unify: false
 
   config:
     install_tree:
diff --git a/share/spack/gitlab/cloud_pipelines/stacks/e4s-oneapi/spack.yaml b/share/spack/gitlab/cloud_pipelines/stacks/e4s-oneapi/spack.yaml
index ce8441a5d87..944c110ac54 100644
--- a/share/spack/gitlab/cloud_pipelines/stacks/e4s-oneapi/spack.yaml
+++ b/share/spack/gitlab/cloud_pipelines/stacks/e4s-oneapi/spack.yaml
@@ -3,7 +3,7 @@ spack:
 
   concretizer:
     reuse: false
-    unify: when_possible
+    unify: false
 
   config:
     concretizer: clingo