John Oliver just demolished Donald Trump’s wall.

On Sunday night’s episode of Last Week Tonight, Oliver spent 18 minutes setting off a series of controlled explosions, destroying Trump’s proposed Mexican border wall before it could even be built. 

The best thing about this segment is that Oliver takes Trump’s proposal seriously. “The border wall is one of the few policy proposals Trump has talked about in detail,” he said, “so instead of mocking or dismissing it out of hand, tonight let’s take a serious proposal by a serious presidential candidate seriously.” 

But, as Oliver points out, there are a lot of problems with Trump’s proposal. The wall is expensive, would require relocating hundreds of families, and it can’t even be built on the actual border.