diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index c2ca1940a..fe4db1ba0 100755
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -16,10 +16,10 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest]
         args:
         - "--resolver nightly --stack-yaml stack-nightly.yaml"
+        - "--resolver lts-21"
+        - "--resolver lts-20 --stack-yaml stack-lts-20.yaml"
         - "--resolver lts-19"
         - "--resolver lts-18"
-        - "--resolver lts-17 --stack-yaml stack-lts-17.yaml"
-        - "--resolver lts-16 --stack-yaml stack-lts-17.yaml"
 
     steps:
       - name: Clone project
diff --git a/stack-lts-20.yaml b/stack-lts-20.yaml
new file mode 100644
index 000000000..7f6cdc41b
--- /dev/null
+++ b/stack-lts-20.yaml
@@ -0,0 +1,31 @@
+resolver: lts-20.26
+packages:
+- ./recv
+- ./auto-update
+- ./mime-types
+- ./wai
+- ./wai-extra
+- ./warp
+- ./warp-tls
+- ./wai-app-static
+- ./wai-frontend-monadcgi
+- ./wai-http2-extra
+- ./wai-websockets
+- ./wai-conduit
+- ./time-manager
+flags:
+  wai-extra:
+    build-example: true
+nix:
+  enable: false
+  packages:
+  - fcgi
+  - zlib
+extra-deps:
+  - crypton-0.33
+  - crypton-x509-1.7.6
+  - crypton-x509-store-1.6.9
+  - crypton-x509-validation-1.6.12
+  - tls-1.8.0
+  - cgi-3001.5.0.1
+  - multipart-0.2.1
diff --git a/stack-nightly.yaml b/stack-nightly.yaml
index f6974a6ea..2256c9a29 100644
--- a/stack-nightly.yaml
+++ b/stack-nightly.yaml
@@ -1,4 +1,4 @@
-resolver: nightly-2020-01-08
+resolver: nightly-2023-09-09
 packages:
 - ./recv
 - ./auto-update
@@ -8,8 +8,7 @@ packages:
 - ./warp
 - ./warp-tls
 - ./wai-app-static
-# 'cgi' package isn't up to date
-# - ./wai-frontend-monadcgi
+- ./wai-frontend-monadcgi
 - ./wai-http2-extra
 - ./wai-websockets
 - ./wai-conduit
diff --git a/stack.yaml b/stack.yaml
index be9a89c69..2dde447ea 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-18.28
+resolver: lts-21.11
 packages:
 - ./recv
 - ./auto-update
@@ -21,4 +21,9 @@ nix:
   packages:
   - fcgi
   - zlib
-extra-deps: []
+extra-deps:
+  - crypton-0.33
+  - crypton-x509-1.7.6
+  - crypton-x509-store-1.6.9
+  - crypton-x509-validation-1.6.12
+  - tls-1.8.0