diff --git a/lib/capybara/config.rb b/lib/capybara/config.rb
index 4af9d197..0122f2bb 100644
--- a/lib/capybara/config.rb
+++ b/lib/capybara/config.rb
@@ -20,6 +20,7 @@ module Capybara
 
     def initialize
       @session_options = Capybara::SessionConfig.new
+      @javascript_driver = nil
     end
 
     attr_writer :reuse_server
diff --git a/lib/capybara/spec/session/node_wrapper_spec.rb b/lib/capybara/spec/session/node_wrapper_spec.rb
index 50d782e2..3e4b2e73 100644
--- a/lib/capybara/spec/session/node_wrapper_spec.rb
+++ b/lib/capybara/spec/session/node_wrapper_spec.rb
@@ -1,15 +1,15 @@
 # frozen_string_literal: true
 
+class NodeWrapper
+  def initialize(element); @element = element end
+  def to_capybara_node(); @element end
+end
+
 Capybara::SpecHelper.spec "#to_capybara_node" do
   before do
     @session.visit('/with_html')
   end
 
-  class NodeWrapper
-    def initialize(element); @element = element end
-    def to_capybara_node(); @element end
-  end
-
   it "should support have_xxx expectations" do
     para = NodeWrapper.new(@session.find(:css, '#first'))
     expect(para).to have_link("ullamco")
diff --git a/spec/session_spec.rb b/spec/session_spec.rb
index 2a932900..29d7130b 100644
--- a/spec/session_spec.rb
+++ b/spec/session_spec.rb
@@ -18,6 +18,12 @@ RSpec.describe Capybara::Session do
   end
 
   context "current_driver" do
+    around do |example|
+      orig_driver = Capybara.current_driver
+      example.run
+      Capybara.current_driver = orig_driver
+    end
+
     it "is global when threadsafe false" do
       Capybara.threadsafe = false
       Capybara.current_driver = :selenium
@@ -40,6 +46,12 @@ RSpec.describe Capybara::Session do
   end
 
   context "session_name" do
+    around do |example|
+      orig_name = Capybara.session_name
+      example.run
+      Capybara.session_name = orig_name
+    end
+
     it "is global when threadsafe false" do
       Capybara.threadsafe = false
       Capybara.session_name = "sess1"