Force to accept GPS coordinates & not “correct” them

I often need to tweak the GPS coordinates of images I take with my iPhone. Since I work on a MBP laptop, I do it there. A workflow: use a map app to find the precise location of the photo. Enter those coordinates into the location field in the Get Info box of the image. Watch decide what I “meant” and move the coordinates to what it thinks is the closest place. This is often a what it thinks a city’s coordinates are when I feed it a location inside that city.

The question then is how I make it stop doing this. I can move the pin, of course, or just use something like exiftool to edit the image’s data directly, but it seems like this should be doable within Photos.

Then again…