Fatal error message

I was just installing the Read More Right Here plugin. Everything seemed to be going fine. When I clicked the Activate Plugin link I got this message:

Fatal error: Call to undefined function: strripos() in /home/content/m/s/p/msprof75/html/wordpress/wp-content/plugins/read-more-right-here/read-more-right-here.php on line 42

Is this fixable? If so, how do I go about it?

Thanks in advance for the help.