diff --git a/apply-merge.cabal b/apply-merge.cabal
index 235afe4..59cfbb9 100644
--- a/apply-merge.cabal
+++ b/apply-merge.cabal
@@ -30,6 +30,7 @@ tested-with:
   , GHC == 9.6.6
   , GHC == 9.8.4
   , GHC == 9.10.1
+  , GHC == 9.12.1
 extra-doc-files:
     README.md
     CHANGELOG.md
@@ -59,7 +60,7 @@ library
   ghc-options: -Wall
   build-depends:
       array ==0.5.*
-    , base >=4.9 && <4.10 || >=4.10 && <4.11 || >=4.11 && <4.12 || >=4.12 && <4.13 || >=4.13 && <4.14 || >=4.14 && <4.15 || >=4.15 && <4.16 || >=4.16 && <4.17 || >=4.17 && <4.18 || >=4.18 && <4.19 || >=4.19 && <4.20 || >=4.20 && <4.21
+    , base >=4.9 && <4.10 || >=4.10 && <4.11 || >=4.11 && <4.12 || >=4.12 && <4.13 || >=4.13 && <4.14 || >=4.14 && <4.15 || >=4.15 && <4.16 || >=4.16 && <4.17 || >=4.17 && <4.18 || >=4.18 && <4.19 || >=4.19 && <4.20 || >=4.20 && <4.21 || >=4.21 && <4.22
     , containers >=0.6 && <0.7 || >=0.7 && <0.8
     , pqueue >=1.4 && <1.5 || >=1.5 && <1.6
     , reflection ==2.1.*
@@ -101,7 +102,7 @@ test-suite apply-merge-tests
   ghc-options: -Wall
   build-depends:
       array ==0.5.*
-    , base >=4.9 && <4.10 || >=4.10 && <4.11 || >=4.11 && <4.12 || >=4.12 && <4.13 || >=4.13 && <4.14 || >=4.14 && <4.15 || >=4.15 && <4.16 || >=4.16 && <4.17 || >=4.17 && <4.18 || >=4.18 && <4.19 || >=4.19 && <4.20 || >=4.20 && <4.21
+    , base >=4.9 && <4.10 || >=4.10 && <4.11 || >=4.11 && <4.12 || >=4.12 && <4.13 || >=4.13 && <4.14 || >=4.14 && <4.15 || >=4.15 && <4.16 || >=4.16 && <4.17 || >=4.17 && <4.18 || >=4.18 && <4.19 || >=4.19 && <4.20 || >=4.20 && <4.21 || >=4.21 && <4.22
     , containers >=0.6 && <0.7 || >=0.7 && <0.8
     , data-ordlist ==0.4.*
     , pqueue >=1.4 && <1.5 || >=1.5 && <1.6
@@ -146,7 +147,7 @@ benchmark apply-merge-benchmarks
   ghc-options: -Wall
   build-depends:
       array ==0.5.*
-    , base >=4.9 && <4.10 || >=4.10 && <4.11 || >=4.11 && <4.12 || >=4.12 && <4.13 || >=4.13 && <4.14 || >=4.14 && <4.15 || >=4.15 && <4.16 || >=4.16 && <4.17 || >=4.17 && <4.18 || >=4.18 && <4.19 || >=4.19 && <4.20 || >=4.20 && <4.21
+    , base >=4.9 && <4.10 || >=4.10 && <4.11 || >=4.11 && <4.12 || >=4.12 && <4.13 || >=4.13 && <4.14 || >=4.14 && <4.15 || >=4.15 && <4.16 || >=4.16 && <4.17 || >=4.17 && <4.18 || >=4.18 && <4.19 || >=4.19 && <4.20 || >=4.20 && <4.21 || >=4.21 && <4.22
     , containers >=0.6 && <0.7 || >=0.7 && <0.8
     , data-ordlist ==0.4.*
     , pqueue >=1.4 && <1.5 || >=1.5 && <1.6
diff --git a/package.yaml b/package.yaml
index ae16823..5f89a85 100644
--- a/package.yaml
+++ b/package.yaml
@@ -26,6 +26,7 @@ tested-with:
 - GHC == 9.6.6
 - GHC == 9.8.4
 - GHC == 9.10.1
+- GHC == 9.12.1
 
 extra-doc-files:
 - README.md
@@ -52,7 +53,7 @@ when:
   - -Wunused-packages
 
 dependencies:
-- base ^>= {4.9, 4.10, 4.11, 4.12, 4.13, 4.14, 4.15, 4.16, 4.17, 4.18, 4.19, 4.20}
+- base ^>= {4.9, 4.10, 4.11, 4.12, 4.13, 4.14, 4.15, 4.16, 4.17, 4.18, 4.19, 4.20, 4.21}
 
 library:
   source-dirs: src