diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bd52a15..e5fcb0b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,12 +11,14 @@ jobs:
     runs-on: ubuntu-latest
 
     strategy:
+      fail-fast: false
       matrix:
         gemfile:
           - Gemfile.rails-5.0-stable
           - Gemfile.rails-5.1-stable
           - Gemfile.rails-5.2-stable
           - Gemfile.rails-6.0-stable
+          - Gemfile.rails-6.1-stable
     env:
       BUNDLE_GEMFILE: gemfiles/${{ matrix.gemfile }}
     steps:
@@ -25,6 +27,8 @@ jobs:
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: "2.6"
-          bundler-cache: true
+      - name: Install dependencies
+        run: bundle install
       - name: Run tests
-        run: bundle exec rspec
+        run:
+          bundle exec rspec
diff --git a/gemfiles/Gemfile.rails-5.0-stable.lock b/gemfiles/Gemfile.rails-5.0-stable.lock
deleted file mode 100644
index 300c6b1..0000000
--- a/gemfiles/Gemfile.rails-5.0-stable.lock
+++ /dev/null
@@ -1,74 +0,0 @@
-GIT
-  remote: https://github.com/rails/rails.git
-  revision: ac6aa32f7cf66264ba87eabed7c042bb60bcf3a2
-  branch: 5-0-stable
-  specs:
-    activemodel (5.0.7.2)
-      activesupport (= 5.0.7.2)
-    activerecord (5.0.7.2)
-      activemodel (= 5.0.7.2)
-      activesupport (= 5.0.7.2)
-      arel (~> 7.0)
-    activesupport (5.0.7.2)
-      concurrent-ruby (~> 1.0, >= 1.0.2)
-      i18n (>= 0.7, < 2)
-      minitest (~> 5.1)
-      tzinfo (~> 1.1)
-
-PATH
-  remote: ..
-  specs:
-    polymorphic_integer_type (3.0.0)
-      activerecord (< 6.1)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    arel (7.1.4)
-    byebug (11.1.3)
-    coderay (1.1.3)
-    concurrent-ruby (1.1.8)
-    diff-lcs (1.4.4)
-    i18n (1.8.10)
-      concurrent-ruby (~> 1.0)
-    method_source (1.0.0)
-    minitest (5.14.4)
-    pry (0.13.1)
-      coderay (~> 1.1)
-      method_source (~> 1.0)
-    pry-byebug (3.9.0)
-      byebug (~> 11.0)
-      pry (~> 0.13.0)
-    rake (13.0.3)
-    rspec (3.10.0)
-      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.10.0)
-    rspec-core (3.10.1)
-      rspec-support (~> 3.10.0)
-    rspec-expectations (3.10.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-mocks (3.10.2)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-support (3.10.2)
-    sqlite3 (1.3.13)
-    thread_safe (0.3.6)
-    tzinfo (1.2.9)
-      thread_safe (~> 0.1)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activerecord!
-  bundler
-  polymorphic_integer_type!
-  pry-byebug
-  rake
-  rspec
-  sqlite3 (~> 1.3.6)
-
-BUNDLED WITH
-   2.1.4
diff --git a/gemfiles/Gemfile.rails-5.1-stable.lock b/gemfiles/Gemfile.rails-5.1-stable.lock
deleted file mode 100644
index 070ca95..0000000
--- a/gemfiles/Gemfile.rails-5.1-stable.lock
+++ /dev/null
@@ -1,74 +0,0 @@
-GIT
-  remote: https://github.com/rails/rails.git
-  revision: 663206d20aec374a28a24bb43bc7b1233042ed9b
-  branch: 5-1-stable
-  specs:
-    activemodel (5.1.7)
-      activesupport (= 5.1.7)
-    activerecord (5.1.7)
-      activemodel (= 5.1.7)
-      activesupport (= 5.1.7)
-      arel (~> 8.0)
-    activesupport (5.1.7)
-      concurrent-ruby (~> 1.0, >= 1.0.2)
-      i18n (>= 0.7, < 2)
-      minitest (~> 5.1)
-      tzinfo (~> 1.1)
-
-PATH
-  remote: ..
-  specs:
-    polymorphic_integer_type (3.0.0)
-      activerecord (< 6.1)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    arel (8.0.0)
-    byebug (11.1.3)
-    coderay (1.1.3)
-    concurrent-ruby (1.1.8)
-    diff-lcs (1.4.4)
-    i18n (1.8.10)
-      concurrent-ruby (~> 1.0)
-    method_source (1.0.0)
-    minitest (5.14.4)
-    pry (0.13.1)
-      coderay (~> 1.1)
-      method_source (~> 1.0)
-    pry-byebug (3.9.0)
-      byebug (~> 11.0)
-      pry (~> 0.13.0)
-    rake (13.0.3)
-    rspec (3.10.0)
-      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.10.0)
-    rspec-core (3.10.1)
-      rspec-support (~> 3.10.0)
-    rspec-expectations (3.10.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-mocks (3.10.2)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-support (3.10.2)
-    sqlite3 (1.4.2)
-    thread_safe (0.3.6)
-    tzinfo (1.2.9)
-      thread_safe (~> 0.1)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activerecord!
-  bundler
-  polymorphic_integer_type!
-  pry-byebug
-  rake
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   2.1.4
diff --git a/gemfiles/Gemfile.rails-5.2-stable.lock b/gemfiles/Gemfile.rails-5.2-stable.lock
deleted file mode 100644
index d12ecde..0000000
--- a/gemfiles/Gemfile.rails-5.2-stable.lock
+++ /dev/null
@@ -1,74 +0,0 @@
-GIT
-  remote: https://github.com/rails/rails.git
-  revision: 48661542a2607d55f436438fe21001d262e61fec
-  branch: 5-2-stable
-  specs:
-    activemodel (5.2.6)
-      activesupport (= 5.2.6)
-    activerecord (5.2.6)
-      activemodel (= 5.2.6)
-      activesupport (= 5.2.6)
-      arel (>= 9.0)
-    activesupport (5.2.6)
-      concurrent-ruby (~> 1.0, >= 1.0.2)
-      i18n (>= 0.7, < 2)
-      minitest (~> 5.1)
-      tzinfo (~> 1.1)
-
-PATH
-  remote: ..
-  specs:
-    polymorphic_integer_type (3.0.0)
-      activerecord (< 6.1)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    arel (9.0.0)
-    byebug (11.1.3)
-    coderay (1.1.3)
-    concurrent-ruby (1.1.8)
-    diff-lcs (1.4.4)
-    i18n (1.8.10)
-      concurrent-ruby (~> 1.0)
-    method_source (1.0.0)
-    minitest (5.14.4)
-    pry (0.13.1)
-      coderay (~> 1.1)
-      method_source (~> 1.0)
-    pry-byebug (3.9.0)
-      byebug (~> 11.0)
-      pry (~> 0.13.0)
-    rake (13.0.3)
-    rspec (3.10.0)
-      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.10.0)
-    rspec-core (3.10.1)
-      rspec-support (~> 3.10.0)
-    rspec-expectations (3.10.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-mocks (3.10.2)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-support (3.10.2)
-    sqlite3 (1.4.2)
-    thread_safe (0.3.6)
-    tzinfo (1.2.9)
-      thread_safe (~> 0.1)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activerecord!
-  bundler
-  polymorphic_integer_type!
-  pry-byebug
-  rake
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   2.1.4
diff --git a/gemfiles/Gemfile.rails-6.0-stable.lock b/gemfiles/Gemfile.rails-6.0-stable.lock
deleted file mode 100644
index 07288b4..0000000
--- a/gemfiles/Gemfile.rails-6.0-stable.lock
+++ /dev/null
@@ -1,74 +0,0 @@
-GIT
-  remote: https://github.com/rails/rails.git
-  revision: ef97441036e0ebbe1aa2108d59c408707f998ffd
-  branch: 6-0-stable
-  specs:
-    activemodel (6.0.3.7)
-      activesupport (= 6.0.3.7)
-    activerecord (6.0.3.7)
-      activemodel (= 6.0.3.7)
-      activesupport (= 6.0.3.7)
-    activesupport (6.0.3.7)
-      concurrent-ruby (~> 1.0, >= 1.0.2)
-      i18n (>= 0.7, < 2)
-      minitest (~> 5.1)
-      tzinfo (~> 1.1)
-      zeitwerk (~> 2.2, >= 2.2.2)
-
-PATH
-  remote: ..
-  specs:
-    polymorphic_integer_type (3.0.0)
-      activerecord (< 6.1)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    byebug (11.1.3)
-    coderay (1.1.3)
-    concurrent-ruby (1.1.8)
-    diff-lcs (1.4.4)
-    i18n (1.8.10)
-      concurrent-ruby (~> 1.0)
-    method_source (1.0.0)
-    minitest (5.14.4)
-    pry (0.13.1)
-      coderay (~> 1.1)
-      method_source (~> 1.0)
-    pry-byebug (3.9.0)
-      byebug (~> 11.0)
-      pry (~> 0.13.0)
-    rake (13.0.3)
-    rspec (3.10.0)
-      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.10.0)
-    rspec-core (3.10.1)
-      rspec-support (~> 3.10.0)
-    rspec-expectations (3.10.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-mocks (3.10.2)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-support (3.10.2)
-    sqlite3 (1.4.2)
-    thread_safe (0.3.6)
-    tzinfo (1.2.9)
-      thread_safe (~> 0.1)
-    zeitwerk (2.4.2)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  activerecord!
-  bundler
-  polymorphic_integer_type!
-  pry-byebug
-  rake
-  rspec
-  sqlite3
-
-BUNDLED WITH
-   2.1.4
diff --git a/gemfiles/Gemfile.rails-6.1-stable b/gemfiles/Gemfile.rails-6.1-stable
new file mode 100644
index 0000000..a50681f
--- /dev/null
+++ b/gemfiles/Gemfile.rails-6.1-stable
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "activerecord", github: "rails/rails", branch: "6-1-stable"
diff --git a/lib/polymorphic_integer_type/activerecord_5_0_0/polymorphic_array_value_extension.rb b/lib/polymorphic_integer_type/activerecord_5_0_0/polymorphic_array_value_extension.rb
index eb386ee..7f1fc5e 100644
--- a/lib/polymorphic_integer_type/activerecord_5_0_0/polymorphic_array_value_extension.rb
+++ b/lib/polymorphic_integer_type/activerecord_5_0_0/polymorphic_array_value_extension.rb
@@ -10,7 +10,12 @@ module PolymorphicArrayValueExtension
     # end
 
     def type_to_ids_mapping
-      association = @associated_table.send(:association)
+      if ACTIVE_RECORD_VERSION < Gem::Version.new("6.1")
+        association = @associated_table.send(:association)
+      else
+        association = @associated_table.send(:reflection)
+      end
+
       name = association.name
       default_hash = Hash.new { |hsh, key| hsh[key] = [] }
       values.each_with_object(default_hash) do |value, hash|
diff --git a/lib/polymorphic_integer_type/belongs_to_polymorphic_association_extension.rb b/lib/polymorphic_integer_type/belongs_to_polymorphic_association_extension.rb
index edb21cd..8840fc2 100644
--- a/lib/polymorphic_integer_type/belongs_to_polymorphic_association_extension.rb
+++ b/lib/polymorphic_integer_type/belongs_to_polymorphic_association_extension.rb
@@ -1,10 +1,17 @@
 module ActiveRecord
   module Associations
     class BelongsToPolymorphicAssociation < BelongsToAssociation
-      private def replace_keys(record)
-        super
-        unless record.nil?
-          owner[reflection.foreign_type] = record.class.base_class
+      private
+
+      if Gem::Version.new(ActiveRecord::VERSION::STRING) < Gem::Version.new("6.1")
+        def replace_keys(record)
+          super
+          owner[reflection.foreign_type] = record.class.base_class unless record.nil?
+        end
+      elsif
+        def replace_keys(record, force: false)
+          super
+          owner[reflection.foreign_type] = record.class.base_class unless record.nil?
         end
       end
     end
diff --git a/polymorphic_integer_type.gemspec b/polymorphic_integer_type.gemspec
index 1230f50..b226df3 100644
--- a/polymorphic_integer_type.gemspec
+++ b/polymorphic_integer_type.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "activerecord", "< 6.1"
+  spec.add_dependency "activerecord", "< 7"
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec"