diff --git a/rb/Gemfile.lock b/rb/Gemfile.lock
index 550939a6d3b70..f6ee830661149 100644
--- a/rb/Gemfile.lock
+++ b/rb/Gemfile.lock
@@ -3,7 +3,7 @@ PATH
   specs:
     selenium-devtools (0.124.0)
       selenium-webdriver (~> 4.2)
-    selenium-webdriver (4.20.1)
+    selenium-webdriver (4.21.0.nightly)
       base64 (~> 0.2)
       rexml (~> 3.2, >= 3.2.5)
       rubyzip (>= 1.2.2, < 3.0)
diff --git a/rb/lib/selenium/webdriver/version.rb b/rb/lib/selenium/webdriver/version.rb
index f4c276cad2c6e..7dab164bc68b8 100644
--- a/rb/lib/selenium/webdriver/version.rb
+++ b/rb/lib/selenium/webdriver/version.rb
@@ -19,6 +19,6 @@
 
 module Selenium
   module WebDriver
-    VERSION = '4.20.1'
+    VERSION = '4.21.0.nightly'
   end # WebDriver
 end # Selenium