Charlie Ebersol's mother doesn't approve of Britney Spears.

Susan Saint James - whose TV producer son is dating the 'Toxic' hitmaker - reportedly ''can't believe'' that the couple is ''getting serious''.

A source close to Susan revealed: ''Charlie introduced Britney to the both of them as his girlfriend. But they do not agree about her.

''Dick [Ebersol; Charlie's father] thinks it is great to see his son happy, but Susan wants him to be with someone not famous.''

They also revealed that Susan doesn't think her son has made the ''right choice''.

The insider added to RadarOnline.com: ''All Charlie's mother has ever wanted is for him to get married and have children.

''She just doesn't think Britney is the right choice.''

Previously, a source revealed that Britney's family has done the opposite and given her boyfriend the seal of approval.

The source shared: ''He does well financially and is very private.

''They don't have to worry about whether he is using Britney.''

Meanwhile, the 'Piece of Me' hitmaker - who turned 33 on Tuesday (02.12.14) - received a personalised birthday cake from Charlie to mark the occasion.

A source previously explained: ''Charlie has been a longtime client of Duff's Cakemix and he wanted to specifically design this for her from him.

''Every detail came straight from his creative, sweet brain.''