diff --git a/docs/tpm_not_working.md b/docs/tpm_not_working.md
index 87d2998..f92a432 100644
--- a/docs/tpm_not_working.md
+++ b/docs/tpm_not_working.md
@@ -16,6 +16,16 @@ Related [issue #22](https://github.com/tmux-plugins/tpm/issues/22)
- ZSH tmux plugin might be causing issues.
If you have it installed, try disabling it and see if `tpm` works then.
+- Are you using `tmux` as a top level shell?
+ If `tmux` is the top level shell (not started from another shell) then the
+ environment during initialisation could be very minimal. For example, if your
+ `tmux` binary is under `/usr/local/bin` (as it is in macOS when installed with
+ Homebrew) then `tpm` will not find it since `/usr/local/bin` might not be in
+ the `$PATH`. A workaround would be to extend the `$PATH` manually in
+ `.tmux.conf` before loading `tpm`:
+
+ set-environment -g "PATH" "/usr/local/bin:$PATH"
+