diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9ea543b..7493b1e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -6,7 +6,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        ruby: ["ruby-head", "3.4", "3.3", "3.2"]
+        ruby: ["ruby-head", "4.0.0-preview3", "3.4", "3.3", "3.2"]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v6
@@ -16,7 +16,7 @@ jobs:
             ~/.cargo/registry
             ~/.cargo/git
             tmp
-          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          key: ${{ runner.os }}-${{ matrix.ruby }}-cargo-${{ hashFiles('**/Cargo.lock') }}
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}