diff --git a/lib/persistent_selenium/browser.rb b/lib/persistent_selenium/browser.rb
index 2ba2d5c..2acd757 100644
--- a/lib/persistent_selenium/browser.rb
+++ b/lib/persistent_selenium/browser.rb
@@ -6,6 +6,7 @@ module PersistentSelenium
   class Browser < Capybara::Selenium::Driver
     def initialize(browser_type)
       @browser_type = browser_type.to_s.to_sym
+      @frame_handles = {}
       @__found_elements__ = []
     end