diff --git a/.github/workflows/gradle-build.yml b/.github/workflows/gradle-build.yml
index 5ad8f67..a46c52e 100644
--- a/.github/workflows/gradle-build.yml
+++ b/.github/workflows/gradle-build.yml
@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java-version: [ 8, 11, 17, 21 ]
+        java-version: [ "8", "11", "17", "21" ]
     steps:
       - name: Check out project
         uses: actions/checkout@v4