diff --git a/rb/lib/selenium/devtools.rb b/rb/lib/selenium/devtools.rb
index a40116117616f..1bcef03a3d7bf 100644
--- a/rb/lib/selenium/devtools.rb
+++ b/rb/lib/selenium/devtools.rb
@@ -17,6 +17,8 @@
 # specific language governing permissions and limitations
 # under the License.
 
+require 'websocket'
+
 module Selenium
   module DevTools
     class << self