diff --git a/tmux.1 b/tmux.1
index c90b5560..55f88c98 100644
--- a/tmux.1
+++ b/tmux.1
@@ -110,6 +110,10 @@ The options are as follows:
 Force
 .Nm
 to assume the terminal supports 256 colours.
+.It Fl a Ar file
+Limit access to the public keys listed in the
+.Ar file
+given as argument.
 .It Fl C
 Start in control mode (see the
 .Sx CONTROL MODE
diff --git a/tmux.c b/tmux.c
index 53b984d7..730c2dfc 100644
--- a/tmux.c
+++ b/tmux.c
@@ -68,6 +68,7 @@ usage(void)
 	    " -F           set the foreground mode, useful for setting remote access\n"
 	    " -f <path>    set the config file path\n"
 	    " -S <path>    set the socket path, useful to issue commands to a running tmate instance\n"
+	    " -a <path>    limit access to ssh public keys listed in provided file\n"
 	    " -v           set verbosity (can be repeated)\n"
 	    " -V           print version\n"
 	    ,__progname);