diff --git a/.github/workflows/ci-unit-tests-os.yml b/.github/workflows/ci-unit-tests-os.yml
index 33fd7362248..9f06142ddc2 100644
--- a/.github/workflows/ci-unit-tests-os.yml
+++ b/.github/workflows/ci-unit-tests-os.yml
@@ -80,7 +80,7 @@ jobs:
         os: [ubuntu-latest]
         rust: [stable, beta]
         # When vars.EXPERIMENTAL_FEATURES is empty this should become a single matrix item
-        features: ${{ ["", vars.EXPERIMENTAL_FEATURES ] }}
+        features: ${{ fromJSON(format('["", {0}]', vars.EXPERIMENTAL_FEATURES)) }}
         exclude:
         # We're excluding macOS beta for the following reasons:
         # - the concurrent macOS runner limit is much lower than the Linux limit