diff --git a/tmux/tmux.conf b/tmux/tmux.conf
index dcc87ed..d37c7b7 100644
--- a/tmux/tmux.conf
+++ b/tmux/tmux.conf
@@ -57,6 +57,8 @@ set-option -g focus-events on
 
 # Terminal feature specific to Neovim
 set-option -sa terminal-overrides ',kitty:Tc'
+set -as terminal-overrides ',*:Smulx=\E[4::%p1%dm'  # undercurl support
+set -as terminal-overrides ',*:Setulc=\E[58::2::%p1%{65536}%/%d::%p1%{256}%/%{255}%&%d::%p1%{255}%&%d%;m'  # underscore colours - needs tmux-3.0
 
 # Tmux plugins
 set -g @plugin "janoamaral/tokyo-night-tmux"