diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index 95d6f6b8..0e0f2f52 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -25,6 +25,6 @@ jobs:
           dune-cache: true
           allow-prerelease-opam: true
 
-      - run: opam install ocamlformat.0.27.0
+      - run: opam install ocamlformat.0.27.0 lwt.6.1.1
       - run: opam exec -- make format-check