Regex wildcard “+” not getting saved

I’m trying to use the following regex expression which appears to be a valid php regex expression:

^.*\/post\/\d+\/(.*)

However, whenever I save it the “+” gets dropped and this is what is saved:

^.*\/post\/\d \/(.*)

And thus it doesn’t work as expected. If I change the regex to a specific number of digits then it works fine, example:

^.*\/post\/\d{12}\/(.*)

However, I can’t be certain they will always have 12 digits in the URL string.

Thanks