diff --git a/.github/workflows/packdeps.yml b/.github/workflows/packdeps.yml
new file mode 100644
index 0000000..376312a
--- /dev/null
+++ b/.github/workflows/packdeps.yml
@@ -0,0 +1,40 @@
+name: Packdeps
+
+on:
+  workflow_dispatch:
+  schedule:
+    # Run every Saturday
+    - cron: '0 3 * * 6'
+
+jobs:
+  packdeps:
+    name: Packdeps
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Clone project
+        uses: actions/checkout@v2
+      - name: Setup Haskell
+        uses: haskell/actions/setup@v1
+        with:
+          # packdeps doesn't build with newer as of 2021-10
+          ghc-version: '8.8'
+      - name: Install packdeps
+        run: |
+          set -ex
+          echo "$HOME/.cabal/bin" >> $GITHUB_PATH
+          cabal install packdeps
+      - name: Check package bounds (all)
+        continue-on-error: true
+        run: |
+          set -ex
+          packdeps \
+            --exclude X11 \
+            *.cabal
+      - name: Check package bounds (preferred)
+        run: |
+          set -ex
+          packdeps \
+            --preferred \
+            --exclude X11 \
+            *.cabal
diff --git a/.github/workflows/stack.yml b/.github/workflows/stack.yml
index 02a2fbe..db6d700 100644
--- a/.github/workflows/stack.yml
+++ b/.github/workflows/stack.yml
@@ -20,6 +20,8 @@ jobs:
             ghc: 8.8.4
           - resolver: lts-17
             ghc: 8.10.4
+          - resolver: lts-18
+            ghc: 8.10.7
 
     steps:
       - name: Clone project
@@ -43,7 +45,8 @@ jobs:
             #
 
       - name: Install GHC
-        # use system ghc in stack, don't waste GH Actions cache space
+        # use system ghc (if available) in stack, don't waste GH Actions cache space
+        continue-on-error: true
         run: |
           set -ex
           sudo apt install -y ghc-${{ matrix.ghc }}
@@ -70,6 +73,7 @@ jobs:
           path: |
             ~/.stack/*
             !~/.stack/pantry
+            !~/.stack/programs
           key: stack-${{ runner.os }}-${{ matrix.resolver }}-${{ steps.cache-date.outputs.date }}-${{ hashFiles('stack.yaml') }}-${{ hashFiles('*.cabal') }}
           restore-keys: |
             stack-${{ runner.os }}-${{ matrix.resolver }}-${{ steps.cache-date.outputs.date }}-${{ hashFiles('stack.yaml') }}-
diff --git a/MAINTAINERS.md b/MAINTAINERS.md
index 58b4a13..9e604a1 100644
--- a/MAINTAINERS.md
+++ b/MAINTAINERS.md
@@ -78,10 +78,9 @@ When the time comes to release another version of xmonad and xmonad-contrib:
 
      If the manpage changes, wait for the CI to rebuild the rendered outputs.
 
-  3. Check dependency bounds. In particular, [packdeps][] can be used to check
-     if any new versions are excluded by the upper bounds specified.
-     Also, make sure that `tested-with:` covers several recent releases of
-     GHC, and that `.github/workflows/stack.yml` tests with several recent
+  3. Make sure that `tested-with:` covers several recent releases of GHC, that
+     `.github/workflows/haskell-ci.yml` had been updated to test all these GHC
+     versions and that `.github/workflows/stack.yml` tests with several recent
      revisions of [Stackage][] LTS.
 
   4. Create a release on GitHub:
@@ -105,9 +104,12 @@ When the time comes to release another version of xmonad and xmonad-contrib:
 
   7. Post announcement to:
 
+     - [xmonad.org website](https://github.com/xmonad/xmonad-web/tree/gh-pages/news/_posts)
      - [XMonad mailing list](https://mail.haskell.org/mailman/listinfo/xmonad)
      - [Haskell Cafe](https://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe)
      - [Haskell Discourse](https://discourse.haskell.org/)
+     - [Twitter](https://twitter.com/xmonad)
+     - [Reddit](https://www.reddit.com/r/xmonad/)
 
      See [old announcements][old-announce] for inspiration.
 
diff --git a/xmonad.cabal b/xmonad.cabal
index a9d3c0c..22f24cb 100644
--- a/xmonad.cabal
+++ b/xmonad.cabal
@@ -67,7 +67,7 @@ library
                    XMonad.StackSet
   other-modules:   Paths_xmonad
   hs-source-dirs:  src
-  build-depends:   base                  >= 4.9 && < 5
+  build-depends:   base                  >= 4.11 && < 5
                  , X11                   >= 1.10 && < 1.11
                  , containers
                  , data-default-class