diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cd99957e8..3bfa687a2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -289,6 +289,7 @@ jobs:
           continue-on-error: true
         - SWIGLANG: ocaml
           continue-on-error: true
+          os: ubuntu-18.04 # ocaml-4.08 in ubuntu-20.04 not yet working
       # Run all of them, as opposed to aborting when one fails
       fail-fast: false