diff --git a/lib/redis-session-store.rb b/lib/redis-session-store.rb
index 9e3514a..187ccb1 100644
--- a/lib/redis-session-store.rb
+++ b/lib/redis-session-store.rb
@@ -4,14 +4,6 @@
 # the MemCacheStore code, simply dropping in Redis instead.
 class RedisSessionStore < ActionDispatch::Session::AbstractSecureStore
   VERSION = '0.11.5'.freeze
-  # Rails 3.1 and beyond defines the constant elsewhere
-  unless defined?(ENV_SESSION_OPTIONS_KEY)
-    ENV_SESSION_OPTIONS_KEY = if Rack.release.split('.').first.to_i > 1
-                                Rack::RACK_SESSION_OPTIONS
-                              else
-                                Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY
-                              end
-  end
 
   USE_INDIFFERENT_ACCESS = defined?(ActiveSupport).freeze
   # ==== Options
@@ -156,7 +148,7 @@ def set_session(env, sid, session_data, options = nil)
   alias write_session set_session
 
   def get_expiry(env, options)
-    session_storage_options = options || env.fetch(ENV_SESSION_OPTIONS_KEY, {})
+    session_storage_options = options || env.fetch(Rack::RACK_SESSION_OPTIONS, {})
     session_storage_options[:ttl] || session_storage_options[:expire_after]
   end
 
diff --git a/spec/redis_session_store_spec.rb b/spec/redis_session_store_spec.rb
index 51dee2f..35a2770 100644
--- a/spec/redis_session_store_spec.rb
+++ b/spec/redis_session_store_spec.rb
@@ -151,71 +151,6 @@
     end
   end
 
-  describe 'rack 1.45 compatibility' do
-    # Rack 1.45 (which Rails 3.2.x depends on) uses the return value of
-    # set_session to set the cookie value.  See:
-    # https://github.com/rack/rack/blob/1.4.5/lib/rack/session/abstract/id.rb
-
-    let(:env)          { double('env') }
-    let(:session_id)   { Rack::Session::SessionId.new('12 345') }
-    let(:session_data) { double('session_data') }
-    let(:options)      { { expire_after: 123 } }
-
-    context 'when successfully persisting the session' do
-      it 'returns the session id' do
-        expect(store.send(:set_session, env, session_id, session_data, options))
-          .to eq(session_id)
-      end
-    end
-
-    context 'when unsuccessfully persisting the session' do
-      before do
-        allow(store).to receive(:redis).and_raise(Redis::CannotConnectError)
-      end
-
-      it 'returns false' do
-        expect(store.send(:set_session, env, session_id, session_data, options))
-          .to eq(false)
-      end
-    end
-
-    context 'when no expire_after option is given' do
-      let(:options) { {} }
-
-      it 'sets the session value without expiry' do
-        expect(store.send(:set_session, env, session_id, session_data, options))
-          .to eq(session_id)
-      end
-    end
-
-    context 'when redis is down' do
-      before do
-        allow(store).to receive(:redis).and_raise(Redis::CannotConnectError)
-        store.on_redis_down = ->(*_a) { @redis_down_handled = true }
-      end
-
-      it 'returns false' do
-        expect(store.send(:set_session, env, session_id, session_data, options))
-          .to eq(false)
-      end
-
-      it 'calls the on_redis_down handler' do
-        store.send(:set_session, env, session_id, session_data, options)
-        expect(@redis_down_handled).to eq(true)
-      end
-
-      context 'when :on_redis_down re-raises' do
-        before { store.on_redis_down = ->(e, *) { raise e } }
-
-        it 'explodes' do
-          expect do
-            store.send(:set_session, env, session_id, session_data, options)
-          end.to raise_error(Redis::CannotConnectError)
-        end
-      end
-    end
-  end
-
   describe 'checking for session existence' do
     let(:public_id) { 'foo' }
     let(:session_id) { Rack::Session::SessionId.new(public_id) }
diff --git a/spec/support.rb b/spec/support.rb
index 1d009e6..cfdd2e6 100644
--- a/spec/support.rb
+++ b/spec/support.rb
@@ -1,86 +1,5 @@
-unless defined?(Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY)
-  module Rack
-    module Session
-      module Abstract
-        ENV_SESSION_OPTIONS_KEY = 'rack.session.options'.freeze
-      end
-    end
-  end
-end
-unless defined?(Rack::Session::SessionId)
-  module Rack
-    module Session
-      class SessionId
-        ID_VERSION = 2
+require "rack/session/abstract/id"
 
-        attr_reader :public_id
-
-        def initialize(public_id)
-          @public_id = public_id
-        end
-
-        alias to_s public_id
-
-        def empty?
-          false
-        end
-
-        def inspect
-          public_id.inspect
-        end
-
-        def private_id
-          "#{ID_VERSION}::#{hash_sid(public_id)}"
-        end
-
-        private
-
-        def hash_sid(value)
-          "test_hash_from:#{value}"
-        end
-      end
-    end
-  end
-end
-
-unless defined?(ActionDispatch::Session::AbstractSecureStore)
-  module ActionDispatch
-    module Session
-      class AbstractSecureStore
-        ENV_SESSION_OPTIONS_KEY = 'rack.session.options'.freeze
-        DEFAULT_OPTIONS = {
-          key: '_session_id',
-          path: '/',
-          domain: nil,
-          expire_after: nil,
-          secure: false,
-          httponly: true,
-          cookie_only: true
-        }.freeze
-
-        def initialize(app, options = {})
-          @app = app
-          @default_options = DEFAULT_OPTIONS.dup.merge(options)
-          @key = @default_options[:key]
-          @cookie_only = @default_options[:cookie_only]
-        end
-
-        private
-
-        def generate_sid
-          Rack::Session::SessionId.new(rand(999..9999).to_s(16))
-        end
-      end
-    end
-  end
-end
-
-unless defined?(Rails)
-  require 'logger'
-
-  module Rails
-    def self.logger
-      @logger ||= Logger.new('/dev/null')
-    end
-  end
-end
+require "active_support/message_encryptor"
+require "active_support/core_ext/hash/indifferent_access"
+require "action_dispatch/middleware/session/abstract_store"