tmate is a fork of tmux for easily setting up a remote pairing session. When using normal tmux, I have the following configuration so that new panes and windows remember the previous working path:

bind-key - split-window -v  -c '#{pane_current_path}'
bind-key \ split-window -h  -c '#{pane_current_path}'
bind c new-window -c '#{pane_current_path}'

I recently tried remote pairing in tmate for the first time. It was confused as to why my new panes and windows were opening in the top level / instead of the previous pane’s path.

It turns out that pane_current_path is a tmux 1.9 feature, but tmate is based on tmux 1.8. There’s some talk of a 1.9 version, but it seems to have been delayed.

The workaround I’ve found is to use -c "$PWD" instead. Make sure to use double quotes so that it gets interpolated. You can add that to ~/.tmate.conf to override the existing setting in ~/.tmux.conf.