N-400, Application for Naturalization, Country of Birth

I am a Russian citizen filing N-400. The N-400 form has a drop-down list "Country of Birth", where both are available, "Russia" and "Soviet Union". The N-400 instructions clearly say "Use the name of the country at the time of your birth, even if the name of the country has changed." I was born in 1987, i. e. in the Soviet Union before it ended its existence in 1991, and per instructions, I must specify "Soviet Union". On my GC, however, I have "Russia" in the "Country of Birth" field, and not "Soviet Union". The reason is that when I filled out the documents for the GC, i. e. the I-485 form, 5+ years ago, there was no clear guidance on which country to specify, and I chose "Russia", as it officially exists today, and not "Soviet Union". My question is what exactly is the right course of action in my case? "Soviet Union" seems to be the way to proceed, yet in this case, there will be a mismatch between my GC where I have "Russia", and N-400, where I will have "Soviet Union".