diff --git a/actionpack/lib/action_dispatch/testing/integration.rb b/actionpack/lib/action_dispatch/testing/integration.rb
index 13f7fc6fa6..f5ec28a9c2 100644
--- a/actionpack/lib/action_dispatch/testing/integration.rb
+++ b/actionpack/lib/action_dispatch/testing/integration.rb
@@ -420,9 +420,13 @@ module ActionDispatch
 
       attr_reader :app
 
+      def initialize(*args, &blk)
+        super(*args, &blk)
+        @integration_session = nil
+      end
+
       def before_setup # :nodoc:
         @app = nil
-        @integration_session = nil
         super
       end
 
diff --git a/actionpack/test/dispatch/runner_test.rb b/actionpack/test/dispatch/runner_test.rb
new file mode 100644
index 0000000000..969933c9ed
--- /dev/null
+++ b/actionpack/test/dispatch/runner_test.rb
@@ -0,0 +1,18 @@
+require "abstract_unit"
+
+class RunnerTest < ActiveSupport::TestCase
+  test "runner preserves the setting of integration_session" do
+    runner = Class.new do
+      def before_setup
+
+      end
+    end.new
+
+    runner.extend(ActionDispatch::Integration::Runner)
+    runner.integration_session.host! "lvh.me"
+
+    runner.before_setup
+
+    assert_equal "lvh.me", runner.integration_session.host
+  end
+end