diff --git a/spack.yaml b/spack.yaml
index 79a50ce88aaf27dc7191813bb7dc648cb8827455..e354b341bf041a1f796361216d75e5cc7d08fcdd 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -8,19 +8,18 @@ spack:
 
   definitions:
   - compiler-pkgs:
+    - 'gcc@9.3.1 os=centos7'
     - 'gcc@10.3.0 os=centos7'
   - pkgs:
-    # start ultra-simple...
-    #- libsigsegv
-    # start simple...
-    #- gawk
-    #- m4
-    # interesing but still quite plain software
-    #- nest +gsl
-    #- arbor
-    # BrainScaleS
-    - visionary-dls-core ^py-astroid@2.4.2 ^py-setuptools-scm+toml ^python@3.8.9
+    - python@3.8.10
+    - py-numpy ^python@3.8.10
+    - py-scipy ^python@3.8.10
+    - py-pip ^python@3.8.10
+    - nest +gsl +python ^python@3.8.10
+    - arbor
+
   - compilers:
+    - '%gcc@9.3.1'
     - '%gcc@10.3.0'
 #    - '%gcc@4.8.5'
   - oses:
@@ -33,11 +32,11 @@ spack:
     - [$oses]
 
   mirrors:
-    #mirror: s3://spack-public/mirror
-    #cloud_gitlab: https://mirror.spack.io
-    local_something: /builds/emuller/brainscales-spack-test/local_mirror
+    mirror: s3://spack-public/mirror
+    cloud_gitlab: https://mirror.spack.io
+    #local_something: /builds/emuller/brainscales-spack-test/local_mirror
     # build_cache/ gets added
-    hacky_cache: https://brainscales-r.kip.uni-heidelberg.de:7443/nmpi/tmp
+    #hacky_cache: https://brainscales-r.kip.uni-heidelberg.de:7443/nmpi/tmp
 
   gitlab-ci:
     bootstrap: