diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1e212fe..226b05f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -26,7 +26,7 @@ jobs:
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.julia-version }}
-      - run: echo "${{ flat(toJSON(matrix)) }}"
+      - run: echo "${{ join(toJSON(matrix || ''), '-') }}"
       - uses: julia-actions/cache@e728574ebe1cca247c00e20b177387a41b086d6f
       - uses: julia-actions/julia-runtest@v1
         with: