diff --git a/src/lucky_flow/selenium/chrome/driver.cr b/src/lucky_flow/selenium/chrome/driver.cr
index 7e00f1b..915ea39 100644
--- a/src/lucky_flow/selenium/chrome/driver.cr
+++ b/src/lucky_flow/selenium/chrome/driver.cr
@@ -24,12 +24,12 @@ end
 
 LuckyFlow::Registry.register :headless_chrome do
   LuckyFlow::Selenium::Chrome::Driver.new do |config|
-    remote_debuggin_port = ENV["CHROME_REMOTE_DEBUGGING_PORT"]? || 9222
+    remote_debugging_port = ENV.fetch("CHROME_REMOTE_DEBUGGING_PORT", "9222")
     config.chrome_options.args = [
       "no-sandbox",
       "headless",
       "disable-gpu",
-      "remote-debugging-port=#{remote_debuggin_port}",
+      "remote-debugging-port=#{remote_debugging_port}",
     ]
   end
 end
diff --git a/src/lucky_flow/selenium/firefox/driver.cr b/src/lucky_flow/selenium/firefox/driver.cr
index d7d1388..8747cdf 100644
--- a/src/lucky_flow/selenium/firefox/driver.cr
+++ b/src/lucky_flow/selenium/firefox/driver.cr
@@ -24,14 +24,14 @@ end
 
 LuckyFlow::Registry.register :headless_firefox do
   LuckyFlow::Selenium::Firefox::Driver.new do |config|
-    remote_debuggin_port = ENV["FIREFOX_REMOTE_DEBUGGING_PORT"]? || 9222
+    remote_debugging_port = ENV.fetch("FIREFOX_REMOTE_DEBUGGING_PORT", "9222")
     config.firefox_options.args = [
       "--headless",
       "--disable-gpu",
       "--disable-software-rasterizer",
       "--no-sandbox",
       "--disable-dev-shm-usage",
-      "--start-debugger-server=#{remote_debuggin_port}",
+      "--start-debugger-server=#{remote_debugging_port}",
     ]
   end
 end