diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0ea9ef2..b4dd8df 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -98,15 +98,15 @@ jobs:
       run: |
         cabal run stan
 
-  # As at 2023-12-16, the GitHub-hosted runner for ubuntu-latest comes with
-  # Stack 2.13.1 and GHC 9.8.1.
+  # As at 2024-05-06, the GitHub-hosted runner for ubuntu-latest comes with
+  # Stack 2.15.5 and GHC 9.8.2.
   stack:
     name: stack / ghc ${{ matrix.ghc }}
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ghc: ["9.6.3"] # The version specified in the stack.yaml file
-        cache-bust: ["2023-12-16"]
+        ghc: ["9.6.5"] # The version specified in the stack.yaml file
+        cache-bust: ["2024-05-06"]
 
     steps:
     - name: Clone project
diff --git a/stack-ghc-9.6.3.yaml b/stack-ghc-9.6.3.yaml
index 339567a..941a954 100644
--- a/stack-ghc-9.6.3.yaml
+++ b/stack-ghc-9.6.3.yaml
@@ -3,7 +3,7 @@ resolver: lts-22.6 # GHC 9.6.3
 extra-deps:
 - ansi-wl-pprint-0.6.9@sha256:fb737bc96e2aef34ad595d54ced7a73f648c521ebcb00fe0679aff45ccd49212,2448
 - dir-traverse-0.2.3.0@sha256:adcc128f201ff95131b15ffe41365dc99c50dc3fa3a910f021521dc734013bfa,2137
-- extensions-0.1.0.1@sha256:f365d1da5ea1c60edd11334113ecd0d78eb12b4186b31151322ff7175a9adef7,5108
+- extensions-0.1.0.1@sha256:131270f3dd3adfa96e48259a200b7303c4f8211f54bff168fb8020dfef2aaec7,5269
 - optparse-applicative-0.17.1.0@sha256:cb5f5f0dc9749846fc0e3df0041a8efee6368cc1cff07336acd4c3b02a951ed6,5147
 - tomland-1.3.3.2@sha256:887dc39a8c9819deb8fcb6fde72e87dad4c94108b1736a5bf7215ccf3117bd0f,9474
 - trial-0.0.0.0@sha256:ebd93f3485dd7f0ce8426fa46b500f26edbea285c2890150123e1b0f6a92c7db,4410
diff --git a/stack-ghc-9.6.4.yaml b/stack-ghc-9.6.4.yaml
new file mode 100644
index 0000000..c92cdd2
--- /dev/null
+++ b/stack-ghc-9.6.4.yaml
@@ -0,0 +1,12 @@
+resolver: lts-22.20 # GHC 9.6.4
+
+extra-deps:
+- ansi-wl-pprint-0.6.9@sha256:fb737bc96e2aef34ad595d54ced7a73f648c521ebcb00fe0679aff45ccd49212,2448
+- dir-traverse-0.2.3.0@sha256:adcc128f201ff95131b15ffe41365dc99c50dc3fa3a910f021521dc734013bfa,2137
+- extensions-0.1.0.1@sha256:131270f3dd3adfa96e48259a200b7303c4f8211f54bff168fb8020dfef2aaec7,5269
+- optparse-applicative-0.17.1.0@sha256:cb5f5f0dc9749846fc0e3df0041a8efee6368cc1cff07336acd4c3b02a951ed6,5147
+- tomland-1.3.3.2@sha256:887dc39a8c9819deb8fcb6fde72e87dad4c94108b1736a5bf7215ccf3117bd0f,9474
+- trial-0.0.0.0@sha256:ebd93f3485dd7f0ce8426fa46b500f26edbea285c2890150123e1b0f6a92c7db,4410
+- trial-optparse-applicative-0.0.0.0@sha256:ee878dbf412849d4fb52d7bca93bec45a6392a93e03a46bd320109b9a0ff2a38,2540
+- trial-tomland-0.0.0.0@sha256:c10c5c3f94e3dcfcad4a66cf70682ace77d5381596aff91fa2030636d07de977,2541
+- validation-selective-0.2.0.0@sha256:e1ab5482dede8bf676d729a09109c7c5f798363b9d458e4197a27afb8b48fdd3,3907
diff --git a/stack.yaml b/stack.yaml
index 290ed99..b1e702a 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,9 +1,9 @@
-resolver: lts-22.7 # GHC 9.6.4
+resolver: lts-22.21 # GHC 9.6.5
 
 extra-deps:
 - ansi-wl-pprint-0.6.9@sha256:fb737bc96e2aef34ad595d54ced7a73f648c521ebcb00fe0679aff45ccd49212,2448
 - dir-traverse-0.2.3.0@sha256:adcc128f201ff95131b15ffe41365dc99c50dc3fa3a910f021521dc734013bfa,2137
-- extensions-0.1.0.1@sha256:f365d1da5ea1c60edd11334113ecd0d78eb12b4186b31151322ff7175a9adef7,5108
+- extensions-0.1.0.1@sha256:131270f3dd3adfa96e48259a200b7303c4f8211f54bff168fb8020dfef2aaec7,5269
 - optparse-applicative-0.17.1.0@sha256:cb5f5f0dc9749846fc0e3df0041a8efee6368cc1cff07336acd4c3b02a951ed6,5147
 - tomland-1.3.3.2@sha256:887dc39a8c9819deb8fcb6fde72e87dad4c94108b1736a5bf7215ccf3117bd0f,9474
 - trial-0.0.0.0@sha256:ebd93f3485dd7f0ce8426fa46b500f26edbea285c2890150123e1b0f6a92c7db,4410
diff --git a/stan.cabal b/stan.cabal
index 1cc1714..d2202cc 100644
--- a/stan.cabal
+++ b/stan.cabal
@@ -20,6 +20,7 @@ extra-doc-files:     README.md
 extra-source-files:  test/.stan-example.toml
                      stack-ghc-9.4.8.yaml
                      stack-ghc-9.6.3.yaml
+                     stack-ghc-9.6.4.yaml
                      stack.yaml
 tested-with:         GHC == 8.8.4
                      GHC == 8.10.7