java.lang.classnotfoundexception: org.openqa.selenium.io.Circular OutputStream

I was just creating a simple test project with Selenium v2 (Webdriver) and for headless testing, I added the PhantomJS driver dependency as follows with other dependencies:

<dependency>
    <groupId>com.github.detro</groupId>
    <artifactId>phantomjsdriver</artifactId>
    <version>1.2.0</version>
</dependency>

But it is getting error:

java.lang.NoClassDefFoundError: org/openqa/selenium/io/CircularOutputStream
at org.openqa.selenium.firefox.FirefoxBinary.<init>(FirefoxBinary.java:60)
at org.openqa.selenium.firefox.FirefoxBinary.<init>(FirefoxBinary.java:56)
at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:120)
at jp.co.skygate.home.HomePageLogin.setUp(HomePageLogin.java:108)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at

Just removing the Phantom jS dependency solves the problem and it executes fine. Can someone help me find the problem?

Thanks in advance