function or operator to ignore metacharacters like +

Hi,
I have this line that I have problem with..

s/$tmpvar//mgi;

The problem is sometimes $tmpvar = "annotationmarking +",
with metacharacters. Is there a regx option or perl function
that ignores metacharacter. Or should I go ahead and
parse my input for metacharacters and add a \ infront of it.

Thanks.

JP

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