diff --git a/README.md b/README.md
index 3aa49a4..f1c33ac 100644
--- a/README.md
+++ b/README.md
@@ -83,6 +83,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
+        # Due to a bug discussed on https://github.com/actions/runner/issues/849, we have to use quotes for '3.0'
         ruby: [2.5, 2.6, 2.7, '3.0', head, jruby, jruby-head, truffleruby, truffleruby-head]
     runs-on: ${{ matrix.os }}
     steps: