diff --git a/stack-ghc9.4.7.yaml b/stack-ghc9.4.7.yaml
index 30d516125..78e8153d0 100644
--- a/stack-ghc9.4.7.yaml
+++ b/stack-ghc9.4.7.yaml
@@ -1,7 +1,7 @@
-resolver: lts-21.18 # GHC-9.4.7
+resolver: lts-21.20 # GHC-9.4.7
 
-extra-deps:
-- multipart-0.2.0@sha256:b8770e3ff6089be4dd089a8250894b31287cca671f3d258190a505f9351fa8a9,1084
-- cgi-3001.5.0.0@sha256:3d1193a328d5f627a021a0ef3927c1ae41dd341e32dba612fed52d0e3a6df056,2990
+# extra-deps:
+# - multipart-0.2.0@sha256:b8770e3ff6089be4dd089a8250894b31287cca671f3d258190a505f9351fa8a9,1084
+# - cgi-3001.5.0.0@sha256:3d1193a328d5f627a021a0ef3927c1ae41dd341e32dba612fed52d0e3a6df056,2990
 
 allow-newer: true
diff --git a/stack.yaml b/stack.yaml
index 3cacaef6d..ea948ee61 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -2,11 +2,11 @@
 # But committing a symlink can be problematic on Windows, so it's a real copy.
 # See: https://github.com/GrammaticalFramework/gf-core/pull/106
 
-resolver: lts-21.18
+resolver: lts-21.20
 
-extra-deps:
-- multipart-0.2.1@sha256:c96322a5bb34c29738ba82345d071a8e07d752648de3522f1c04d96df955ea0d,1150
-- cgi-3001.5.0.1@sha256:4eb5254d65fe00e91f46a8bab5467669e6e95f6a0eb73a048b70a4aab1a5892e,3458
+# extra-deps:
+# - multipart-0.2.1@sha256:c96322a5bb34c29738ba82345d071a8e07d752648de3522f1c04d96df955ea0d,1150
+# - cgi-3001.5.0.1@sha256:4eb5254d65fe00e91f46a8bab5467669e6e95f6a0eb73a048b70a4aab1a5892e,3458
 
 # flags:
 #   gf: