diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+2025-03-07
+        * Version bump (4.3). (#604)
+        * Remove deprecated function Copilot.Library.Utils.(!!). (#599)
+
 2025-01-07
         * Version bump (4.2). (#577)
         * Bump upper version constraint on containers. (#570)
diff --git a/copilot-libraries.cabal b/copilot-libraries.cabal
--- a/copilot-libraries.cabal
+++ b/copilot-libraries.cabal
@@ -1,6 +1,6 @@
 cabal-version:       >=1.10
 name:                copilot-libraries
-version:             4.2
+version:             4.3
 synopsis:            Libraries for the Copilot language.
 description:
   Libraries for the Copilot language.
@@ -41,7 +41,7 @@
                , containers       >= 0.4 && < 0.8
                , mtl              >= 2.0 && < 2.4
                , parsec           >= 2.0 && < 3.2
-               , copilot-language >= 4.2 && < 4.3
+               , copilot-language >= 4.3 && < 4.4
 
   exposed-modules:
       Copilot.Library.Libraries
diff --git a/src/Copilot/Library/Libraries.hs b/src/Copilot/Library/Libraries.hs
--- a/src/Copilot/Library/Libraries.hs
+++ b/src/Copilot/Library/Libraries.hs
@@ -23,6 +23,6 @@
 import Copilot.Library.PTLTL
 import Copilot.Library.Statistics
 import Copilot.Library.RegExp
-import Copilot.Library.Utils      hiding ((!!))
+import Copilot.Library.Utils
 import Copilot.Library.Voting
 import Copilot.Library.Stacks
diff --git a/src/Copilot/Library/Utils.hs b/src/Copilot/Library/Utils.hs
--- a/src/Copilot/Library/Utils.hs
+++ b/src/Copilot/Library/Utils.hs
@@ -13,10 +13,10 @@
          -- ** Scans
          nscanl, nscanr, nscanl1, nscanr1,
          -- ** Indexing
-         case', (!!), (!!!))
+         case', (!!!))
 where
 
-import Copilot.Language hiding ((!!))
+import Copilot.Language
 import qualified Prelude as P
 
 -- | Given a stream, produce an infinite list of streams dropping an increasing
@@ -130,13 +130,6 @@
                    P.++ "length of alternatives list is not "
                    P.++ "greater by one than the length of predicates list"
   in case'' predicates alternatives
-
--- | Index.
---
--- WARNING: Very expensive! Consider using this only for very short lists.
-(!!) :: (Typed a, Eq b, Num b, Typed b) => [Stream a] -> Stream b -> Stream a
-(!!) = (!!!)
-{-# DEPRECATED (!!) "This function is deprecated in Copilot 4. Use (!!!)." #-}
 
 -- | Index.
 --