diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 
 ## Unreleased
 
+## 0.2.1.0 — 2026-09-08
+
+### Changed
+
+- Raise the internal `shikumi` bound to `^>=0.4.0.0` so this package builds
+  against the breaking core release. No change to this package's own API.
+
 ## 0.2.0.0 — 2026-08-07
 
 ### Added
diff --git a/shikumi-okf.cabal b/shikumi-okf.cabal
--- a/shikumi-okf.cabal
+++ b/shikumi-okf.cabal
@@ -1,6 +1,6 @@
 cabal-version:   3.4
 name:            shikumi-okf
-version:         0.2.0.0
+version:         0.2.1.0
 synopsis:
   Generate OKF documentation bundles from shikumi programs (EP-31)
 
@@ -54,7 +54,7 @@
   build-depends:
     , base      >=4.20     && <5
     , okf-core  ^>=0.5.0.0
-    , shikumi   ^>=0.3.0.0
+    , shikumi   ^>=0.4.0.0
     , text      ^>=2.1
 
 executable shikumi-okf-example
@@ -63,8 +63,8 @@
   main-is:        Main.hs
   build-depends:
     , base
-    , shikumi      ^>=0.3.0.0
-    , shikumi-okf  ^>=0.2.0.0
+    , shikumi      ^>=0.4.0.0
+    , shikumi-okf  ^>=0.2.1.0
     , text
 
 test-suite shikumi-okf-test
@@ -81,8 +81,8 @@
     , effectful
     , filepath
     , okf-core     ^>=0.5.0.0
-    , shikumi      ^>=0.3.0.0
-    , shikumi-okf  ^>=0.2.0.0
+    , shikumi      ^>=0.4.0.0
+    , shikumi-okf  ^>=0.2.1.0
     , tasty
     , tasty-hunit
     , text