diff --git a/.github/workflows/cabal.yml b/.github/workflows/cabal.yml
index a8aa1cc..954b9ee 100644
--- a/.github/workflows/cabal.yml
+++ b/.github/workflows/cabal.yml
@@ -12,10 +12,11 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        cabal: ["3.4"]
+        cabal: ["3.6"]
         ghc:
-          - "8.10.4"
           - "8.8.4"
+          - "8.10.7"
+          - "9.0.1"
 
     steps:
     - uses: actions/checkout@v2
diff --git a/.github/workflows/stack.yml b/.github/workflows/stack.yml
index b980874..51d3ce3 100644
--- a/.github/workflows/stack.yml
+++ b/.github/workflows/stack.yml
@@ -11,9 +11,9 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        cabal: ["3.4"]
+        cabal: ["3.6"]
         ghc:
-          - "8.10.4"
+          - "9.0.1"
 
     steps:
     - uses: actions/checkout@v2
diff --git a/changelog.md b/changelog.md
index 8a52fb1..3a844ab 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,9 @@
 The [latest version](https://github.com/blockscope/hpack-dhall/blob/master/changelog.md) of this changelog.
 
+## 0.5.4 - Rewrite the README
+* Require `hpack >= 0.34.6`.
+* Test with GHC `8.8.4`, GHC `8.10.7` and GHC `9.0.1`.
+
 ## 0.5.3 - Rewrite the README
 * Rewrite the README, making it shorter and splitting some details about more
   uses and building into separate docs.
diff --git a/hpack-dhall.cabal b/hpack-dhall.cabal
index 96dfbba..e55b92f 100644
--- a/hpack-dhall.cabal
+++ b/hpack-dhall.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.12
 
--- This file has been generated from package.dhall by hpack version 0.34.5.
+-- This file has been generated from package.dhall by hpack version 0.34.6.
 --
 -- see: https://github.com/sol/hpack
 
@@ -27,7 +27,7 @@ license:        BSD3
 license-file:   LICENSE
 build-type:     Simple
 tested-with:
-    GHC == 8.8.4, GHC == 8.10.7
+    GHC == 8.8.4, GHC == 8.10.7, GHC == 9.0.1
 extra-source-files:
     package.dhall
     changelog.md
diff --git a/package.dhall b/package.dhall
index f397d06..4d8fb56 100644
--- a/package.dhall
+++ b/package.dhall
@@ -41,7 +41,7 @@ in  let exe-deps = [ "optparse-applicative" ]
             and functions.
             ''
         , github = "cabalism/hpack-dhall"
-        , tested-with = "GHC == 8.8.4, GHC == 8.10.7"
+        , tested-with = "GHC == 8.8.4, GHC == 8.10.7, GHC == 9.0.1"
         , extra-source-files =
           [ "package.dhall"
           , "changelog.md"
diff --git a/stack.yaml b/stack.yaml
index 23d7e26..4104af7 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,3 +1,3 @@
-resolver: lts-18.5
+resolver: nightly-2021-12-16
 packages:
 - '.'
\ No newline at end of file
diff --git a/stack.yaml.lock b/stack.yaml.lock
index 04466da..0b4f0d0 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -6,7 +6,7 @@
 packages: []
 snapshots:
 - completed:
-    size: 585817
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/5.yaml
-    sha256: 22d24d0dacad9c1450b9a174c28d203f9bb482a2a8da9710a2f2a9f4afee2887
-  original: lts-18.5
+    size: 611461
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2021/12/16.yaml
+    sha256: 49c66c033e37b259f86219619c27394fa462d1ab18d31e85fbaedfb40262aa28
+  original: nightly-2021-12-16
diff --git a/stack/stack-8.10.4.yaml b/stack/stack-8.10.4.yaml
deleted file mode 100644
index b3d13bd..0000000
--- a/stack/stack-8.10.4.yaml
+++ /dev/null
@@ -1,3 +0,0 @@
-resolver: lts-18.5
-packages:
-- '../'
\ No newline at end of file
diff --git a/stack/stack-8.10.4.yaml.lock b/stack/stack-8.10.4.yaml.lock
deleted file mode 100644
index 04466da..0000000
--- a/stack/stack-8.10.4.yaml.lock
+++ /dev/null
@@ -1,12 +0,0 @@
-# This file was autogenerated by Stack.
-# You should not edit this file by hand.
-# For more information, please see the documentation at:
-#   https://docs.haskellstack.org/en/stable/lock_files
-
-packages: []
-snapshots:
-- completed:
-    size: 585817
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/5.yaml
-    sha256: 22d24d0dacad9c1450b9a174c28d203f9bb482a2a8da9710a2f2a9f4afee2887
-  original: lts-18.5
diff --git a/stack/stack-8.8.4.yaml b/stack/stack-8.8.4.yaml
deleted file mode 100644
index 6673d0b..0000000
--- a/stack/stack-8.8.4.yaml
+++ /dev/null
@@ -1,5 +0,0 @@
-resolver: lts-16.31
-packages:
-- ../
-extra-deps:
-- hpack-0.34.4@sha256:e15193faba0a222389ff86faf52c4d45e91f190f940715e237cf862973537788,4478
\ No newline at end of file
diff --git a/stack/stack-8.8.4.yaml.lock b/stack/stack-8.8.4.yaml.lock
deleted file mode 100644
index cf9eb13..0000000
--- a/stack/stack-8.8.4.yaml.lock
+++ /dev/null
@@ -1,19 +0,0 @@
-# This file was autogenerated by Stack.
-# You should not edit this file by hand.
-# For more information, please see the documentation at:
-#   https://docs.haskellstack.org/en/stable/lock_files
-
-packages:
-- completed:
-    hackage: hpack-0.34.4@sha256:e15193faba0a222389ff86faf52c4d45e91f190f940715e237cf862973537788,4478
-    pantry-tree:
-      size: 3422
-      sha256: 3bedfe2838df1142c836bf94734b06619bb00405aa55fc931d8fcec26fc24742
-  original:
-    hackage: hpack-0.34.4@sha256:e15193faba0a222389ff86faf52c4d45e91f190f940715e237cf862973537788,4478
-snapshots:
-- completed:
-    size: 534126
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/16/31.yaml
-    sha256: 637fb77049b25560622a224845b7acfe81a09fdb6a96a3c75997a10b651667f6
-  original: lts-16.31
diff --git a/stack/stack-9.0.1.yaml b/stack/stack-9.0.1.yaml
index fc6e266..1c01cce 100644
--- a/stack/stack-9.0.1.yaml
+++ b/stack/stack-9.0.1.yaml
@@ -1,3 +1,3 @@
-resolver: nightly-2021-08-08
+resolver: nightly-2021-12-16
 packages:
 - '../'
\ No newline at end of file
diff --git a/stack/stack-9.0.1.yaml.lock b/stack/stack-9.0.1.yaml.lock
index 7598881..0b4f0d0 100644
--- a/stack/stack-9.0.1.yaml.lock
+++ b/stack/stack-9.0.1.yaml.lock
@@ -6,7 +6,7 @@
 packages: []
 snapshots:
 - completed:
-    size: 468990
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2021/6/20.yaml
-    sha256: 103b65064332ba9a92c52101ce6b46c577ef4f8c0eed92fb7c52847719965b81
-  original: nightly-2021-06-20
+    size: 611461
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2021/12/16.yaml
+    sha256: 49c66c033e37b259f86219619c27394fa462d1ab18d31e85fbaedfb40262aa28
+  original: nightly-2021-12-16