diff --git a/.github/workflows/build-check.yml b/.github/workflows/build-check.yml
index 91be05433..1bc3a961d 100644
--- a/.github/workflows/build-check.yml
+++ b/.github/workflows/build-check.yml
@@ -18,6 +18,6 @@ jobs:
           GITHUB_PAT: ${{secrets.GITHUB_TOKEN}}
         with:
           url: "https://github.com/stan-dev/rstan"
-          ref: ""
+          ref: "c1f200f49f2f42e282d47dac9204b6445225ebf7"
           subdir: "StanHeaders"
           branch: "experimental"