diff --git a/tmux.1 b/tmux.1
index b38b43bb..9b874f7b 100644
--- a/tmux.1
+++ b/tmux.1
@@ -3536,7 +3536,7 @@ Lock each client individually by running the command specified by the
 .Ic lock-command
 option.
 .It Xo Ic run-shell
-.Fl b
+.Op Fl b
 .Op Fl t Ar target-pane
 .Ar shell-command
 .Xc