question to sed, doing only on some lines

[astri...@gmail.com]

Hello!

I want to change inplace in a file one string
to another.
But I do not want it to do for the whole file.
I only want it starting at line 46.

I found this:
https://www.grund-wissen.de/linux/shell/sed-und-awk.html

And try this in my sed:
sed -i 46,s/wall/empty/g boundary
but I got this:
sed: -e Ausdruck #1, Zeichen 4: Unerwartetes `,'

How can I get it, that in changes inplace only starting
with line 46?

Regards, Astrid