diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5c5dadd..160c84d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,7 +25,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: ${{ matrix.ruby }}
+          ruby-version: "${{ matrix.ruby }}"
 
       - name: Set up Hotsheet
         run: bin/setup