diff --git a/CHANGELOG.md b/CHANGELOG.md
index b7dc03f0..b2a3e8a8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 5.0.0
+
+### BREAKING CHANGES
+
+* `config` no longer loads `deep_merge`'s monkey patch for `Hash#deep_merge` and `Hash#deep_merge!` ([#342](https://github.com/rubyconfig/config/pull/342)). If you rely on those methods and are not using Rails / Active Support, you can load the monkey patch via `require 'deep_merge/deep_merge_hash'`.
+
 ## 4.2.1
 
 ### Bug fixes
diff --git a/lib/config.rb b/lib/config.rb
index 4713f8ba..5bd5ae11 100644
--- a/lib/config.rb
+++ b/lib/config.rb
@@ -6,7 +6,7 @@
 require 'config/sources/hash_source'
 require 'config/sources/env_source'
 require 'config/validation/schema'
-require 'deep_merge'
+require 'deep_merge/core'
 
 module Config
   extend Config::Validation::Schema