The prospect of a constituent part of a European Union (EU) Member State attaining independence is growing. The year 2012 saw the confirmation of an independence referendum in Scotland, to take place in the fall of 2014, and sub-state nationalism returned to the fore in Spain, Belgium and Italy. Currently, there is no clear mechanism through which to deal with a part of a Member State becoming an independent state. The premise of this article is that such a state of confusion is not conducive to the smooth functioning of the EU. The article argues that, in order to remain faithful to its normative principles and to avoid a dislocation in the single market, the EU must find a way to handle internal enlargement short of expelling new states that might emerge from existing Member States. The official position set out by the European Commission thus needs to be problematised.