diff --git a/spack.yaml b/spack.yaml
index c8f38c11272ff97c8ad37c5db8da3f83f42ba1dc..e59402550933e193ec9c0fa0fdefe620b0fcf605 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -12,11 +12,11 @@ spack:
     - 'gcc@9.3.1 os=centos7'
 #    - 'gcc@10.3.0 os=centos7'
   - pkgs:
-    - 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
+    - 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 %gcc@9.3.1
-    - arbor ^python@3.8.10 %gcc@9.3.1
+    - arbor ^python@3.8.10
 
   - compilers:
 #    - '%gcc@4.8.5'
@@ -28,7 +28,7 @@ spack:
   specs:
   - matrix:
     - [$pkgs]
-#    - [$compilers]
+    - [$compilers]
     - [$oses]
 
   mirrors: