diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 48cd431..96b0699 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,8 +13,8 @@ jobs:
       matrix:
         os:
           - ubuntu-latest
-          - macos-latest
-          #- windows-latest
+          # - macos-latest    # build issues with `ar` (!!!)
+          #- windows-latest   # certificate problem
         ocaml-compiler:
           - 4.03.x
           - 4.12.x