diff --git a/.github/workflows/test_and_deploy.yml b/.github/workflows/test_and_deploy.yml
index 18227a7..d5927af 100644
--- a/.github/workflows/test_and_deploy.yml
+++ b/.github/workflows/test_and_deploy.yml
@@ -31,7 +31,7 @@ jobs:
         include:
         - os: ubuntu-latest
           python-version: "3.11"
-        - os: macos-latest
+        - os: macos-13 # just intel mac here, silicon mac tested with mamba due to niftyreg complications
           python-version: "3.10"
         - os: windows-latest
           python-version: "3.9"
@@ -57,6 +57,7 @@ jobs:
           use-xvfb: true
 
   test-with-conda:
+    # mainly checks conda installation of niftyreg, especially key on Silicon macs
     needs: [linting, manifest]
     name: Test conda-install, on ${{ matrix.os }}
     runs-on: ${{ matrix.os }}