diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 46e219f3..e59d8e7b 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -30,7 +30,13 @@ jobs:
           - no_rails
           - rails_6.1
           - rails_7
+          - rails_7.1
+          - rails_7.2
         exclude:
+          - ruby: 2.7
+            gemfile: rails_7.2
+          - ruby: 3.0
+            gemfile: rails_7.2
           - os: macos
             ruby: head
           - os: windows
@@ -39,6 +45,10 @@ jobs:
             gemfile: rails_6.1
           - os: windows
             gemfile: rails_7
+          - os: windows
+            gemfile: rails_7.1
+          - os: windows
+            gemfile: rails_7.2
         include:
           - ruby: '2.7'
             gemfile: rails_6 # End of life June 1, 2023
diff --git a/ext/oj/mimic_json.c b/ext/oj/mimic_json.c
index 35ad0896..cef9d506 100644
--- a/ext/oj/mimic_json.c
+++ b/ext/oj/mimic_json.c
@@ -905,7 +905,9 @@ oj_define_mimic_json(int argc, VALUE *argv, VALUE self) {
     }
     oj_mimic_json_methods(json);
 
-    rb_define_method(rb_cObject, "to_json", mimic_object_to_json, -1);
+    if (!rb_const_defined(rb_cObject, rb_intern("ActiveSupport"))) {
+        rb_define_method(rb_cObject, "to_json", mimic_object_to_json, -1);
+    }
 
     rb_gv_set("$VERBOSE", verbose);
 
diff --git a/gemfiles/rails_7.1.gemfile b/gemfiles/rails_7.1.gemfile
new file mode 100644
index 00000000..1a4d987c
--- /dev/null
+++ b/gemfiles/rails_7.1.gemfile
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+gem 'rails', '~> 7.1.3'
+gem 'sqlite3'
+gem 'mutex_m'
+gem 'base64'
+gem 'drb'
+
+gemspec :path => '../'
diff --git a/gemfiles/rails_7.2.gemfile b/gemfiles/rails_7.2.gemfile
new file mode 100644
index 00000000..61e1aa56
--- /dev/null
+++ b/gemfiles/rails_7.2.gemfile
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+gem 'rails', '~> 7.2.0'
+gem 'sqlite3'
+gem 'mutex_m'
+gem 'base64'
+gem 'drb'
+
+gemspec :path => '../'
diff --git a/test/activesupport7/abstract_unit.rb b/test/activesupport7/abstract_unit.rb
index 10ff6db8..bd8259cf 100644
--- a/test/activesupport7/abstract_unit.rb
+++ b/test/activesupport7/abstract_unit.rb
@@ -19,7 +19,10 @@
 Thread.abort_on_exception = true
 
 # Show backtraces for deprecated behavior for quicker cleanup.
-ActiveSupport::Deprecation.debug = true
+if ActiveSupport::Deprecation.respond_to?(:debug)
+  # Rails 7.2 does not have ActiveSupport::Deprecation.debug
+  ActiveSupport::Deprecation.debug = true
+end
 
 # Default to old to_time behavior but allow running tests with new behavior
 ActiveSupport.to_time_preserves_timezone = ENV["PRESERVE_TIMEZONES"] == "1"