Pasting diagrams are a very useful device to express composition in higher categories. In the literature there are a number of results on the uniqueness of pastings, starting from John Power’s pasting theorem for 2-categories. For non-strict higher categories there is usually extra work to be done to address various layers of coherence. In this talk I will go through the proof of a pasting theorem for Gray-categories, which gives a foundation to some aspects of the theory of higher derivators I’ve been developing. This is joint work with Dominic Verity.