diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+2024-02-21 Ivan Perez <ivan.perez@keera.co.uk>
+        * Version bump (0.12.2) (#398).
+        * Limit version of transformers to < 0.6 (#405).
+
 2023-12-21 Ivan Perez <ivan.perez@keera.co.uk>
         * Version bump (0.12.1) (#395).
         * Remove postgresql repo before installation in CI script (#392).
diff --git a/dunai.cabal b/dunai.cabal
--- a/dunai.cabal
+++ b/dunai.cabal
@@ -30,7 +30,7 @@
 build-type:    Simple
 
 name:          dunai
-version:       0.12.1
+version:       0.12.2
 author:        Ivan Perez, Manuel Bärenz
 maintainer:    ivan.perez@keera.co.uk
 homepage:      https://github.com/ivanperez-keera/dunai
@@ -129,7 +129,7 @@
       base >= 4.6 && < 5
     , MonadRandom         >= 0.2 && < 0.7
     , simple-affine-space >= 0.2 && < 0.3
-    , transformers        >= 0.3 && < 0.7
+    , transformers        >= 0.3 && < 0.6
     , transformers-base   >= 0.4 && < 0.5
 
   default-language:
@@ -215,7 +215,7 @@
 
   build-depends:
       base         >= 4   && < 5
-    , transformers >= 0.3 && < 0.7
+    , transformers >= 0.3 && < 0.6
     , tasty        >= 0.1 && < 1.5
     , tasty-hunit  >= 0.8 && < 0.11