diff --git a/.github/workflows/nix_tests.yaml b/.github/workflows/nix_tests.yaml
index b6a1ce82..75117a46 100644
--- a/.github/workflows/nix_tests.yaml
+++ b/.github/workflows/nix_tests.yaml
@@ -15,7 +15,8 @@ concurrency:
 
 jobs:
   tests:
-    runs-on: ubuntu-latest
+    runs-on:
+      group: aws-highmemory-32-plus-priv
     steps:
     - uses: actions/checkout@v4
     - uses: cachix/install-nix-action@v27
@@ -29,4 +30,4 @@ jobs:
     - name: Build
       run: nix build
     - name: Run tests.
-      run: nix develop .#impure --command python -m pytest server/tests/
+      run: nix develop .#test --command python -m pytest server/tests/