Positive integer validation on text/numeric price fields

Not sure if this is actually a regression, however:

It is possible to enter negative numbers and fractions into the 'Text/Numeric Quantity' price field.

For example, if you create a new Text/Numeric Quantity field for 'Number of adults' with the price of £10.

When completing the event you can enter

-2

and then the total becomes

-£20

Bargain.

Also, 2.5 adults would make the price £25.

I'm not sure when you wouldn't want these fields to validate 0 or a positive integer only.