diff --git a/.github/workflows/puma.yml b/.github/workflows/puma.yml
index 04e856f8a2..df97d7b2eb 100644
--- a/.github/workflows/puma.yml
+++ b/.github/workflows/puma.yml
@@ -1,5 +1,5 @@
 name: CI
-#  #17  #272
+#  #18  #273
 on: [push, pull_request]
 
 jobs:
@@ -9,6 +9,7 @@ jobs:
     env:
       CI: true
       TESTOPTS: -v
+      MT_CPU: 4
 
     runs-on: ${{ matrix.os }}-latest
     if: |