diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,15 @@
 ## [Unreleased]
 
 
+## [0.4.0.0] — 2026-07-28
+
+### Changed
+
+- Co-released with `keiki-0.4.0.0`; internal `keiki` and
+  `keiki-codec-json` dependency bounds now target the new `^>=0.4` PVP major
+  range introduced by Keiki's typed field-projection API.
+
+
 ## [0.3.1.0] — 2026-07-23
 
 ### Changed
diff --git a/keiki-codec-json.cabal b/keiki-codec-json.cabal
--- a/keiki-codec-json.cabal
+++ b/keiki-codec-json.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               keiki-codec-json
-version:            0.3.1.0
+version:            0.4.0.0
 synopsis:           Optional JSON codec for keiki's RegFile.
 description:
   Sibling package to keiki providing a JSON encoder, decoder, and
@@ -81,7 +81,7 @@
     , aeson             ^>=2.2
     , base              ^>=4.21
     , containers        ^>=0.7
-    , keiki             ^>=0.3
+    , keiki             ^>=0.4
     , scientific        ^>=0.3
     , template-haskell  ^>=2.23
     , text              ^>=2.1
@@ -96,8 +96,8 @@
     , base              ^>=4.21
     , bytestring        ^>=0.12
     , deepseq           ^>=1.5
-    , keiki             ^>=0.3
-    , keiki-codec-json  ^>=0.3
+    , keiki             ^>=0.4
+    , keiki-codec-json  ^>=0.4
     , tasty-bench       ^>=0.4  || ^>=0.5
     , text              ^>=2.1
 
@@ -124,8 +124,8 @@
     , bytestring            ^>=0.12
     , containers            ^>=0.7
     , hspec                 ^>=2.11
-    , keiki                 ^>=0.3
-    , keiki-codec-json      ^>=0.3
+    , keiki                 ^>=0.4
+    , keiki-codec-json      ^>=0.4
     , QuickCheck            ^>=2.15
     , quickcheck-instances  ^>=0.3
     , text                  ^>=2.1