Citizenship for child over 18 years

[VVD]

I am on L1 visa and recently filed I-485 in EB1 category. My child is 17 years old and even if I get my GC in 2021, he will be over 18 years by the time we are eligible for citizenship application (5 years after GC). Will I still be able to file citizenship application for my son along with myself?

Edited December 26, 2020 by VVD
Added missing information

[pontevecchio]

"The Immigration and Nationality Act (INA) defines a child as a person who is both unmarried and under 21 years old."

Also for reference though you should not be affected,

Child Status Protection Act (CSPA) | USCIS

[newacct]

As an adult he can apply for naturalization for himself if he chooses after he turns 18 and he meets the requirements for naturalization as an adult (e.g. he has been a permanent resident for 5 years).