[ is a punctuation character and should be escaped with Ql. Although the

current groff version we have seems to handle it fine, other versions are not
so tolerant.

1 files changed, 1 insertions, 1 deletions

diff --git a/tmux.1 b/tmux.1
index 80283678..f553b18c 100644
--- a/tmux.1
+++ b/tmux.1
@@ -502,7 +502,7 @@ for later insertion into another window.
 This mode is entered with the
 .Ic copy-mode
 command, bound to
-.Ql [
+.Ql \&[
 by default.
 .El
 .Pp