Usage "when he grows up"

In the following sentence is it correct to use the present tense ("when he grows up") with a story that is basically told in the past tense?

Don dreamed of becoming a doctor one day, when he grows up.

• Can "dreamed" (in the past) go with ("when he grows up") in the future?

I don't think that "grew up" can fit, but "grows up" sounds a bit awkward as well.

Tnx, Tommy

My choice in rephrasing this would be:

Don dreamed that one day, when he grew up, he would become a doctor.

Hope that helps.

If you put the subordinate clause first, the problem becomes apparent:"When he grows up, Don dreamed of becoming a doctor one day." The subordinate clause puts us in a possible future, but the main clause puts us in a definite past. You can't posit a past based on an indefinite future.