How do I use MTP?

Hi,

I'm trying to use MTP with llama.cpp, I built from source the mtp-pr, download an MTP model from huggingface https://huggingface.co/unsloth/Qwen3.6-27B-GGUF-MTP/resolve/main/Qwen3.6-27B-Q6_K.gguf

But when I run the model I have an error:

error while handling argument "--spec-type": unknown speculative decoding type without draft model

Can someone tell me what I'm doing wrong?