diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+2025-01-07
+        * Version bump (4.2). (#577)
+        * Bump upper version constraint on containers. (#570)
+
 2024-11-07
         * Version bump (4.1). (#561)
         * Reject duplicate externs in properties and theorems. (#536)
diff --git a/copilot-language.cabal b/copilot-language.cabal
--- a/copilot-language.cabal
+++ b/copilot-language.cabal
@@ -1,6 +1,6 @@
 cabal-version:       >=1.10
 name:                copilot-language
-version:             4.1
+version:             4.2
 synopsis:            A Haskell-embedded DSL for monitoring hard real-time
                      distributed systems.
 description:
@@ -38,13 +38,13 @@
   build-depends: base                  >= 4.9  && < 5
 
                , array                 >= 0.5  && < 0.6
-               , containers            >= 0.4  && < 0.7
+               , containers            >= 0.4  && < 0.8
                , data-reify            >= 0.6  && < 0.7
                , mtl                   >= 2.0  && < 3
 
-               , copilot-core          >= 4.1 && < 4.2
-               , copilot-interpreter   >= 4.1 && < 4.2
-               , copilot-theorem       >= 4.1 && < 4.2
+               , copilot-core          >= 4.2 && < 4.3
+               , copilot-interpreter   >= 4.2 && < 4.3
+               , copilot-theorem       >= 4.2 && < 4.3
 
   exposed-modules: Copilot.Language
                  , Copilot.Language.Operators.BitWise