diff --git a/.github/workflows/mutation.yml b/.github/workflows/mutation.yml
index c15972820..b8ae1df65 100644
--- a/.github/workflows/mutation.yml
+++ b/.github/workflows/mutation.yml
@@ -70,6 +70,6 @@ jobs:
 
       - name: Run infection.
         run: |
-          vendor/bin/infection --threads=2 --ignore-msi-with-no-mutations
+          vendor/bin/infection --threads=1 --ignore-msi-with-no-mutations
         env:
           STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}