diff --git a/lib/standby/active_record/log_subscriber.rb b/lib/standby/active_record/log_subscriber.rb
index 8d2de13..d7e9515 100644
--- a/lib/standby/active_record/log_subscriber.rb
+++ b/lib/standby/active_record/log_subscriber.rb
@@ -1,15 +1,17 @@
+require 'standby/version'
+
 module ActiveRecord
   class LogSubscriber
 
     alias_method :debug_without_standby, :debug
 
     def debug(msg)
-      db = Standby.disabled ? "" : log_header
+      db = Standby.disabled ? '' : log_header
       debug_without_standby(db + msg)
     end
 
     def log_header
-      if Gem::Version.new(ActiveRecord.version) >= Gem::Version.new('7.1')
+      if Standby.version_gte?('7.1')
         color("[#{Thread.current[:_standby] || "primary"}]", ActiveSupport::LogSubscriber::GREEN, bold: true)
       else
         color("[#{Thread.current[:_standby] || "primary"}]", ActiveSupport::LogSubscriber::GREEN, true)
diff --git a/lib/standby/connection_holder.rb b/lib/standby/connection_holder.rb
index cd8cc6e..3dd487d 100644
--- a/lib/standby/connection_holder.rb
+++ b/lib/standby/connection_holder.rb
@@ -6,7 +6,11 @@ class << self
       # for delayed activation
       def activate(target)
         env_name = "#{ActiveRecord::ConnectionHandling::RAILS_ENV.call}_#{target}"
-        spec = ActiveRecord::Base.configurations.find_db_config(env_name)&.configuration_hash
+        if Standby.version_gte?('7.0')
+          spec = ActiveRecord::Base.configurations.find_db_config(env_name)&.configuration_hash
+        else
+          spec = ActiveRecord::Base.configurations[env_name]
+        end
         raise Error, "Standby target '#{target}' is invalid!" if spec.nil?
 
         establish_connection spec
diff --git a/lib/standby/version.rb b/lib/standby/version.rb
index 0c8d1f0..f0d0bba 100644
--- a/lib/standby/version.rb
+++ b/lib/standby/version.rb
@@ -1,3 +1,9 @@
 module Standby
   VERSION = '4.0.0'
+
+  class << self
+    def version_gte?(version)
+      Gem::Version.new(ActiveRecord.version) >= Gem::Version.new(version)
+    end
+  end
 end
diff --git a/spec/configuration_spec.rb b/spec/configuration_spec.rb
index 6676e45..580cfe1 100644
--- a/spec/configuration_spec.rb
+++ b/spec/configuration_spec.rb
@@ -4,9 +4,13 @@
   before do
     # Backup connection and configs
     @backup_conn = Standby.instance_variable_get :@standby_connections
-    @backup_config = ActiveRecord::Base.configurations.configs_for.map do |config|
-      [config.env_name, config.configuration_hash]
-    end.to_h
+    if Standby.version_gte?('7.0')
+      @backup_config = ActiveRecord::Base.configurations.configs_for.map do |config|
+        [config.env_name, config.configuration_hash]
+      end.to_h
+    else
+      @backup_config = ActiveRecord::Base.configurations.dup
+    end
     @backup_disabled = Standby.disabled
     @backup_conn.each_key do |klass_name|
       Object.send(:remove_const, klass_name) if Object.const_defined?(klass_name)
@@ -22,13 +26,21 @@
   end
 
   it 'raises error if standby configuration not specified' do
-    ActiveRecord::Base.configurations = @backup_config.merge({ 'test_standby' => {} })
+    if Standby.version_gte?('7.0')
+      ActiveRecord::Base.configurations = @backup_config.merge({ 'test_standby' => {} })
+    else
+      ActiveRecord::Base.configurations['test_standby'] = nil
+    end
 
     expect { Standby.on_standby { User.count } }.to raise_error(Standby::Error)
   end
 
   it 'connects to primary if standby configuration is disabled' do
-    ActiveRecord::Base.configurations = @backup_config.merge({ 'test_standby' => {} })
+    if Standby.version_gte?('7.0')
+      ActiveRecord::Base.configurations = @backup_config.merge({ 'test_standby' => {} })
+    else
+      ActiveRecord::Base.configurations['test_standby'] = nil
+    end
     Standby.disabled = true
 
     expect(Standby.on_standby { User.count }).to be 2