Overall LGTM, there are a few small things to fix - please have a look at the comments below. http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... File java/client/src/org/openqa/selenium/firefox/FirefoxBinary.java (right): http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... java/client/src/org/openqa/selenium/firefox/FirefoxBinary.java:54: private long timeout = SECONDS.toMillis(45); You could make this list final, since it's initialized in the c'tor. http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... java/client/src/org/openqa/selenium/firefox/FirefoxBinary.java:58: public FirefoxBinary() { Style: Space between the commas. http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... java/client/src/org/openqa/selenium/firefox/FirefoxBinary.java:62: public FirefoxBinary(File pathToFirefoxBinary) { Same. http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... java/client/src/org/openqa/selenium/firefox/FirefoxBinary.java:89: List<String> allParams = Lists.newArrayList(commandLineFlags); According to http://docs.oracle.com/javase/6/docs/api/java/util/List.html#addAll(java.util..., You'll get a NPE if extraArguments is null. Either condition this addition or make sure extraArguments is not null in the c'tor (I prefer the latter). http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... java/client/src/org/openqa/selenium/firefox/FirefoxBinary.java:92: CommandLine command = new CommandLine( Specifying the size here is a bit confusing: You could either create a new String array, pass it to toArray and use it, or just call allParams.toArray(new String[0]); http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... File java/client/src/org/openqa/selenium/firefox/FirefoxDriver.java (right): http://codereview.appspot.com/5633049/diff/1/java/client/src/org/openqa/selen... java/client/src/org/openqa/selenium/firefox/FirefoxDriver.java:128: private static FirefoxBinary getBinary(Capabilities capabilities) { Style: Use spaces rather than tabs for indentation.