illegal string message

Hello all 

I am getting this message

A PHP Error was encountered
Severity: Warning
Message: Illegal string offset '$_GET['companyName']'
Filename: libraries/Profiler.php
Line Number: 276


this is the line code

$output['$_GET['. $key .']'] = htmlspecialchars(stripslashes($val));

Can anybody help?

Cannot seem to figure out what is wrong