diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,11 @@
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## 1.1.2 - 2025-05-09
+
+### Fixed
+- Correct Arbitraty instance for errors.
+
 ## 1.1.1 - 2023-03-14
 
 ### Fixed
diff --git a/json-rpc.cabal b/json-rpc.cabal
--- a/json-rpc.cabal
+++ b/json-rpc.cabal
@@ -1,19 +1,19 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.36.0.
+-- This file has been generated from package.yaml by hpack version 0.38.0.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 0206b1a45ad29041be2d398ab0fc65ed5547443e7527e91e1af6cde940c89694
+-- hash: af79897f0e82fbeacd851e9b286216ab406df7508ea4e6c07e7ced0f24912c64
 
 name:           json-rpc
-version:        1.1.1
+version:        1.1.2
 synopsis:       Fully-featured JSON-RPC 2.0 library
 description:    Please see the README on GitHub at <https://github.com/jprupp/json-rpc#readme>
 category:       Network
 homepage:       https://github.com/jprupp/json-rpc.git#readme
 bug-reports:    https://github.com/jprupp/json-rpc.git/issues
-author:         Jean-Pierre Rupp
+author:         JP Rupp
 maintainer:     jprupp@protonmail.ch
 license:        MIT
 license-file:   LICENSE
diff --git a/src/Network/JSONRPC/Arbitrary.hs b/src/Network/JSONRPC/Arbitrary.hs
--- a/src/Network/JSONRPC/Arbitrary.hs
+++ b/src/Network/JSONRPC/Arbitrary.hs
@@ -34,7 +34,7 @@
 instance Arbitrary ErrorObj where
     arbitrary = oneof
         [ ErrorObj <$> arbitrary <*> arbitrary <*> arbitrary
-        , ErrorVal <$> arbitrary
+        , ErrorVal <$> (arbitrary `suchThat` (/= Null))
         ]
 
 instance Arbitrary BatchRequest where