Hi, I need a small translation from English to Latin.

There is a saying "cogito ergo sum", translating into "I think, therefore I am."

I want to make a similar personal phrase which goes "I dream, therefore I am.'' Online translators say it's "somnium ergo sum", but I don't want to get it wrong because I'm gonna tattoo it. Can someone give the correct translation please?

Thanks in advance :)