As title. With my current setup it looks like this:

But I only want it to use a single color. My current highlight setup:

:hi IndentBlanklineContextStart
IndentBlanklineContextStart xxx cterm=underline gui=underline guisp=#fb5e2a

And, what makes me confused is that this problem only occurs when my neovim is running inside a tmux session. If I run neovim directly without tmux session I got expected behaviour:

  • What's the value of echo $TERM (executed from bash) in outside and inside tmux?
    – 3N4N
    Oct 19, 2022 at 14:15
  • @kadekai: Thanks for your help :) The result of it inside/outside tmux are both alacritty. Not intended to do things in a rush but I also asked the same question on both tmux and alacritty's GitHub repos and got the answer. So hopefully this comment will save your time to help more people :) Oct 19, 2022 at 14:22

1 Answer 1


This answer will only be useful for those who also have this environment setup:

  • You use Alacritty as terminal simulator. (since it support coloring of underlines.)
  • Running neovim inside a tmux session.

When I tried to solve this problem I wasn't sure about the source of it. It turns out this is not related to vi/vim(so sorry about posting it here...), and we only need to add one line in tmux.conf:

set-option -ga terminal-features ",alacritty:usstyle"

If you want to read more context, this is the related issue on GitHub:

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