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Last active April 22, 2024 15:59
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True Color (24-bit) and italics with alacritty + tmux + vim (neovim)

True Color (24-bit) and italics with alacritty + tmux + vim (neovim)

This should make True Color (24-bit) and italics work in your tmux session and vim/neovim when using Alacritty (and should be compatible with any other terminal emulator, including Kitty).

Testing colors

Running this script should look the same in tmux as without.

curl -s >


Configuration files

⚠️ IMPORTANT ⚠️ Don't set $TERM in your shell (zshrc, bashrc, etc.), but your terminal (alacritty).


In ~/.config/alacritty/alacritty.yml:

  TERM: xterm-256color


In ~/.tmux.conf (or ~/.config/tmux/tmux.conf):

set -g default-terminal "tmux-256color"
set -ag terminal-overrides ",xterm-256color:RGB"

# Or use a wildcard instead of forcing a default mode.
# Some users in the comments of this gist have reported that this work better.
#set -sg terminal-overrides ",*:RGB"

# You can also use the env variable set from the terminal.
# Useful if you share your configuration betweeen systems with a varying value.
#set -ag terminal-overrides ",$TERM:RGB"


In ~/.vimrc:

" You might have to force true color when using regular vim inside tmux as the
" colorscheme can appear to be grayscale with "termguicolors" option enabled.
if !has('gui_running') && &term =~ '^\%(screen\|tmux\)'
  let &t_8f = "\<Esc>[38;2;%lu;%lu;%lum"
  let &t_8b = "\<Esc>[48;2;%lu;%lu;%lum"

syntax on
set termguicolors
colorscheme yourfavcolorscheme


If you use ~/.vimrc for your nvim configuration, use the above vim example because it's fully compatible.

💡 neovim recently (Dec 6th 2023) merged some changes that detects termguicolors automatically, so there's no need to set this in an upcoming release. I'll update this notice with a version once released as a public version.

In ~/.config/nvim/init.vim

set termguicolors
colorscheme yourfavcolorscheme

Or ~/.config/nvim/init.lua:

vim.o.termguicolors = true
vim.cmd'colorscheme yourfavcolorscheme'

Not working correctly ?

Check out the comments below for possible solutions.

And if you found another solution I would really appreciate if you left a comment with instructions and the following information:

  • OS/Distro + version
  • Vim or Neovim + version
  • Terminal name + version


Shout-out to the nice folks that provided insightful feedback:

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Appreciate the detailed follow-up on this @mikeslattery. I've updated the article to reflect this 👍

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n0099 commented Feb 29, 2024

echo 'set -as terminal-overrides ",'"$(echo ${TERM%%-*})"'*:Tc"' >> ~/.tmux.conf

tmux must be told that the terminal outside supports RGB colour. This is done by specifying the RGB or Tc terminfo(5) flags. RGB is the official flag, Tc is a tmux extension.

With tmux 3.2 and later this can be added with the terminal-features option:

set -as terminal-features ",gnome*:RGB"

Or for any tmux version the terminal-overrides option:

set -as terminal-overrides ",gnome*:Tc"

and replace gnome with the result of echo ${TERM%%-*} (the first part of $TERM delimited by -) from the terminal emulator that you are currently using outside tmux such as putty or xterm.

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ferBV commented Mar 24, 2024

Just what I needed, thank you a lot.

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