diff --git a/spack.yaml b/spack.yaml
index cee01c2167524531ffcd4fa5c72e9803bad72f1d..6e44a996f7990f6361f71da643a5dd74132de2dc 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -11,12 +11,13 @@ spack:
     - 'gcc@9.3.1 os=centos7'
     - 'gcc@10.3.0 os=centos7'
   - pkgs:
-    - 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
+    - gcc@9.3.1
+    - python@3.8.10 %gcc@9.3.1
+    - py-numpy ^python@3.8.10 %gcc@9.3.1
+    - py-scipy ^python@3.8.10 %gcc@9.3.1
+    - py-pip ^python@3.8.10 %gcc@9.3.1
+    #- nest +gsl +python ^python@3.8.10 %gcc@9.3.1
+    - arbor ^python@3.8.10 %gcc@9.3.1
 
   - compilers:
     - '%gcc@9.3.1'