substitution in many files

[Dave C]

I want to use gnu make to make edits to many files.  In each file, I want to 
substitute the string:

./

to the string

${MPATH}

There could be several instances of this string on one line in the files.

I can do this in perl with:

perl -i -pe 's|\.\/|\${MPATH}\/|g'


but when I put this into a make target, I can not get the character escaping 
right.  The shell always ends up interpreting $MPATH as an empty variable.

Is there a good way to do this in gmake?

thanks,
dave