sed replace inside quotes

Here's a useful sed one-liner:

echo "printf(\"foo\");" > quotemeonthat
sed -i.bak 's/printf("\(.*\)")/printf("\1 is just too lonely without bar")/' quotemeonthat
cat quotemeonthat 

-i.bak - edits the file, preserving the original in quotemeonthat.bak
\1 - refers to the first matched group

output:
printf("foo is just too lonely without bar");

Suggestions for improvements are always welcome :)