Subject-verb agreement. Subject is plural, but not really

Once again I have a line that I wrote for another site that has me a bit bugged.

Months in the freezer is going to pretty much eliminate any risk of consuming a live parasite.

Months is obviously plural, but I'm pretty sure that the line is correct as written.

How?

Or potentially, why not?

Answer

In this sentence, although the time period is a plural of months, we are talking about the single time period.

Three months in the freezer is a noun phrase, and because it is one time period it is singular, so using is is the correct. This is the same reason that we say ten years is a long time to wait instead of ten years are a long time to wait - ten years is a single time period.