Which good book would be great, if you just changed one thing?

Sometimes a science fiction or fantasy novel is like a pure rush of storytelling awesome — with just one fatal flaw, that drags the whole thing down. It's so frustrating, and makes you want to be a backseat author. Which good book would become great, if you made just one change to it?

Please include the book cover or a representative image for your chosen book. And please mention the title and what change you would make. Thanks!

Top image: Book cover art by the amazing Frank Kelly Freas.