diff --git a/src/Control/Monad/Union.hs b/src/Control/Monad/Union.hs
--- a/src/Control/Monad/Union.hs
+++ b/src/Control/Monad/Union.hs
@@ -22,6 +22,7 @@
 import Data.Union.Type (Node (..), Union (..))
 
 import Prelude hiding (lookup)
+import Control.Monad
 import Control.Monad.State
 import Control.Monad.ST
 import Control.Monad.Fix
diff --git a/union-find-array.cabal b/union-find-array.cabal
--- a/union-find-array.cabal
+++ b/union-find-array.cabal
@@ -1,9 +1,9 @@
 name:          union-find-array
-version:       0.1.0.3
+version:       0.1.0.4
 stability:     experimental
 author:        Bertram Felgenhauer
 maintainer:    Bertram Felgenhauer <int-e@gmx.de>
-copyright:     Copyright (c) 2010-2013, Bertram Felgenhauer
+copyright:     Copyright (c) 2010-2014, 2021, 2024, Bertram Felgenhauer
 license:       MIT
 license-file:  LICENSE
 category:      Algorithms, Data
@@ -32,7 +32,7 @@
         Control.Monad.Union
     build-depends:
         array >= 0.3 && < 0.6,
-        mtl >= 1.1 && < 2.3,
+        mtl >= 1.1 && < 2.4,
         base >= 4 && < 5
     default-language: Haskell2010
     other-extensions: