diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 37cc4c40d..985c9ef34 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -15,6 +15,8 @@ jobs:
     steps:
     - name: Setup Ruby
       uses: actions/setup-ruby@v1
+      with:
+        ruby-version: '2.7'
 
     - name: Checkout TinyUSB
       uses: actions/checkout@v2