diff --git a/spack-environment/cuda/spack.yaml b/spack-environment/cuda/spack.yaml
index 450b8705..7af8798f 100644
--- a/spack-environment/cuda/spack.yaml
+++ b/spack-environment/cuda/spack.yaml
@@ -3,8 +3,6 @@ spack:
   - ../concretizer.yaml
   - ../packages.yaml
   - ../view.yaml
-  concretizer:
-    unify: when_possible # multiple epic versions
   specs:
   - acts +cuda cuda_arch=75
   - actsvg
diff --git a/spack-environment/xl/spack.yaml b/spack-environment/xl/spack.yaml
index b3b1e8a3..516dbe64 100644
--- a/spack-environment/xl/spack.yaml
+++ b/spack-environment/xl/spack.yaml
@@ -3,8 +3,6 @@ spack:
   - ../concretizer.yaml
   - ../packages.yaml
   - ../view.yaml
-  concretizer:
-    unify: when_possible # multiple epic versions
   specs:
   - acts
   - actsvg