diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for greskell-core
 
+## 1.0.0.4  -- 2025-01-30
+
+* Support ghc-9.12 (base-4.21).
+
 ## 1.0.0.3  -- 2024-11-05
 
 * Bump dependency version bounds.
diff --git a/greskell-core.cabal b/greskell-core.cabal
--- a/greskell-core.cabal
+++ b/greskell-core.cabal
@@ -1,5 +1,5 @@
 name:                   greskell-core
-version:                1.0.0.3
+version:                1.0.0.4
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -30,7 +30,7 @@
                         Data.Greskell.AsIterator
   other-modules:        Data.Greskell.GraphSON.GraphSONTyped,
                         Data.Greskell.GraphSON.Core
-  build-depends:        base ^>=4.13.0 || ^>=4.14.0 || ^>=4.15.0 || ^>=4.16.0 || ^>=4.17.0 || ^>=4.18.0 || ^>=4.19.0 || ^>=4.20.0,
+  build-depends:        base ^>=4.13.0 || ^>=4.14.0 || ^>=4.15.0 || ^>=4.16.0 || ^>=4.17.0 || ^>=4.18.0 || ^>=4.19.0 || ^>=4.20.0 || ^>=4.21.0,
                         aeson ^>=2.0.2 || ^>=2.1.0 || ^>=2.2.3,
                         unordered-containers ^>=0.2.15,
                         hashable ^>=1.4.0 || ^>=1.5.0,
@@ -56,7 +56,7 @@
                         Data.Greskell.Test.QuickCheck,
                         ExamplesSpec
   build-tool-depends:   hspec-discover:hspec-discover
-  build-depends:        base ^>=4.13.0 || ^>=4.14.0 || ^>=4.15.0 || ^>=4.16.0 || ^>=4.17.0 || ^>=4.18.0 || ^>=4.19.0 || ^>=4.20.0,
+  build-depends:        base ^>=4.13.0 || ^>=4.14.0 || ^>=4.15.0 || ^>=4.16.0 || ^>=4.17.0 || ^>=4.18.0 || ^>=4.19.0 || ^>=4.20.0 || ^>=4.21.0,
                         text ^>=1.2.3 || ^>=2.0.2 || ^>=2.1,
                         aeson ^>=2.0.2 || ^>=2.1.0 || ^>=2.2.3,
                         unordered-containers ^>=0.2.15,
