Newline being inserted after plugin

I created a smarty function called {link_to_template} that creates a URL designed to go inside a <a href=""> - for example: <a href="{link_to_template param1=xyz}">Blah</a> This creates a cache php file with the following: <a href="<?php echo smarty_function_link_to_template(array('param1' => 'xyz'), $this);?> ">Blah</a> There is a single blank line after the ?> (not two in the code above, I inserted one for readability). This was never a problem under php4 - but moving the same site to php5 I get an error now: Fatal error: Cannot use string offset as an array in ... I verified the actual return value in the plugin does NOT contain a newline so it seems smarty is putting it in there. Is there any way to prevent a plugin from automagically inserting a carriage return after the ?> or is there something else I did? Thanks, Josh