diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 8e74a4e844..faa7eb82ff 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -22,7 +22,7 @@ jobs:
 
     - name: install Python packages
       run: |
-        pip install archspec
+        pip install archspec==0.2.2
 
     - name: test eessi_software_subdir.py script
       run: |
diff --git a/.github/workflows/tests_init.yml b/.github/workflows/tests_init.yml
index 38ccbbad31..053acb9730 100644
--- a/.github/workflows/tests_init.yml
+++ b/.github/workflows/tests_init.yml
@@ -22,7 +22,7 @@ jobs:
 
     - name: install Python packages
       run: |
-        pip install archspec pytest
+        pip install archspec==0.2.2 pytest
 
     - name: unit tests for eessi_software_subdir_for_host.py script
       run:
diff --git a/easystacks/pilot.nessi.no/2023.06/eessi-2023.06-eb-4.9.0-2023a.yml b/easystacks/pilot.nessi.no/2023.06/eessi-2023.06-eb-4.9.0-2023a.yml
index 1db0363415..ddc7f53a1e 100644
--- a/easystacks/pilot.nessi.no/2023.06/eessi-2023.06-eb-4.9.0-2023a.yml
+++ b/easystacks/pilot.nessi.no/2023.06/eessi-2023.06-eb-4.9.0-2023a.yml
@@ -45,3 +45,4 @@ easyconfigs:
   - SAMtools-1.18-GCC-12.3.0.eb
   - VCFtools-0.1.16-GCC-12.3.0.eb
   - BEDTools-2.31.0-GCC-12.3.0.eb
+  - PLUMED-2.9.0-foss-2023a.eb