diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7de224fd6..be74463b9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,6 +13,10 @@ jobs:
             archive-command: 'tar --create --bzip2 --file'
             file-extension: 'tar.bz2'
             executable-extension: ''
+          - runner: 'macos-13'
+            archive-command: 'tar --create --bzip2 --file'
+            file-extension: 'tar.bz2'
+            executable-extension: ''
           - runner: 'ubuntu-latest'
             archive-command: 'tar --create --bzip2 --file'
             file-extension: 'tar.bz2'
@@ -37,7 +41,7 @@ jobs:
           submodules: true
       - id: setup-haskell-cabal
         name: "Setup Haskell environment"
-        uses: haskell-actions/setup@v2.5
+        uses: haskell-actions/setup@v2.7
         with:
           enable-stack: true
           stack-version: "latest"
diff --git a/dhall/src/Dhall/Eval.hs b/dhall/src/Dhall/Eval.hs
index aac4b0c28..baeeca77a 100644
--- a/dhall/src/Dhall/Eval.hs
+++ b/dhall/src/Dhall/Eval.hs
@@ -122,7 +122,7 @@ instance Semigroup (VChunks a) where
   VChunks xys z <> VChunks [] z' = VChunks xys (z <> z')
   VChunks xys z <> VChunks ((x', y'):xys') z' = VChunks (xys ++ (z <> x', y'):xys') z'
 
-instance Monoid (VChunks a) where
+instance Monoid (VChunks b) where
   mempty = VChunks [] mempty
 
 {-| Some information is lost when `eval` converts a `Lam` or a built-in function