diff --git a/lib/chewy.rb b/lib/chewy.rb
index b4f91d12e..fdff1bf36 100644
--- a/lib/chewy.rb
+++ b/lib/chewy.rb
@@ -14,7 +14,7 @@
 require 'active_support/core_ext/object/inclusion'
 require 'active_support/core_ext/string/inflections'
 
-require 'i18n/core_ext/hash'
+require 'active_support/core_ext/hash'
 require 'chewy/backports/deep_dup' unless Object.respond_to?(:deep_dup)
 require 'singleton'
 require 'base64'
diff --git a/lib/chewy/index.rb b/lib/chewy/index.rb
index 7c3454461..b415c7167 100644
--- a/lib/chewy/index.rb
+++ b/lib/chewy/index.rb
@@ -236,7 +236,7 @@ def mappings_hash
             raise "Type mapping must have 1 entry: #{type_mapping}"
           end
 
-          fields = type_mapping.reduce[1][:properties]
+          fields = type_mapping.reduce(:merge)[1][:properties]
           fields.each do |field_name, field_settings|
             existing_field_settings = mappings[:properties][field_name]
             if existing_field_settings && existing_field_settings != field_settings
diff --git a/lib/chewy/rspec/update_index.rb b/lib/chewy/rspec/update_index.rb
index 1e505eba9..b8946df81 100644
--- a/lib/chewy/rspec/update_index.rb
+++ b/lib/chewy/rspec/update_index.rb
@@ -1,4 +1,4 @@
-require 'i18n/core_ext/hash'
+require 'active_support/core_ext/hash'
 
 # Rspec matcher `update_index`
 # To use it - add `require 'chewy/rspec'` to the `spec_helper.rb`