diff --git a/plugins/tmux-autoattach/tmux-autoattach.plugin.sh b/plugins/tmux-autoattach/tmux-autoattach.plugin.sh
index 34224c4..42770ef 100644
--- a/plugins/tmux-autoattach/tmux-autoattach.plugin.sh
+++ b/plugins/tmux-autoattach/tmux-autoattach.plugin.sh
@@ -7,12 +7,20 @@
 
 [ -z "$OSH_PLUGIN_TMUX_AUTOATTACH_BEHAVIOR" ] && OSH_PLUGIN_TMUX_AUTOATTACH_BEHAVIOR="detach"
 
+# Note on the option "-As0": tmux-3.0a and before does not attach to a session
+# as far as the session name is not given by "-s SESSION_NAME" [1].  From
+# tmux-3.1, it attaches to an existing session, if any, without specifying the
+# session.  Here, we assume the session name to be "0", which is the default
+# name for the first session.
+#
+# [1] https://github.com/ohmybash/oh-my-bash/pull/332
+
 _osh_plugin_tmux_autoattach_exit() {
-	[ -z "$TMUX" ] && tmux -2u new -A && exit
+	[ -z "$TMUX" ] && tmux -2u new -As0 && exit
 }
 
 _osh_plugin_tmux_autoattach_detach() {
-	[ -z "$TMUX" ] && tmux -2u new -A
+	[ -z "$TMUX" ] && tmux -2u new -As0
 }
 
 case "$OSH_PLUGIN_TMUX_AUTOATTACH_BEHAVIOR" in