diff --git a/cmd-attach-session.c b/cmd-attach-session.c
index 5c8f76ed..07185737 100644
--- a/cmd-attach-session.c
+++ b/cmd-attach-session.c
@@ -39,9 +39,8 @@ const struct cmd_entry cmd_attach_session_entry = {
 };
 
 enum cmd_retval
-cmd_attach_session_exec(struct cmd *self, struct cmd_q *cmdq)
+cmd_attach_session(struct cmd_q *cmdq, const char* tflag, int dflag, int rflag)
 {
-	struct args	*args = self->args;
 	struct session	*s;
 	struct client	*c;
 	const char	*update;
@@ -53,14 +52,14 @@ cmd_attach_session_exec(struct cmd *self, struct cmd_q *cmdq)
 		return (CMD_RETURN_ERROR);
 	}
 
-	if ((s = cmd_find_session(cmdq, args_get(args, 't'), 1)) == NULL)
+	if ((s = cmd_find_session(cmdq, tflag, 1)) == NULL)
 		return (CMD_RETURN_ERROR);
 
 	if (cmdq->client == NULL)
 		return (CMD_RETURN_NORMAL);
 
 	if (cmdq->client->session != NULL) {
-		if (args_has(self->args, 'd')) {
+		if (dflag) {
 			/*
 			 * Can't use server_write_session in case attaching to
 			 * the same session as currently attached to.
@@ -87,10 +86,10 @@ cmd_attach_session_exec(struct cmd *self, struct cmd_q *cmdq)
 			return (CMD_RETURN_ERROR);
 		}
 
-		if (args_has(self->args, 'r'))
+		if (rflag)
 			cmdq->client->flags |= CLIENT_READONLY;
 
-		if (args_has(self->args, 'd'))
+		if (dflag)
 			server_write_session(s, MSG_DETACH, NULL, 0);
 
 		update = options_get_string(&s->options, "update-environment");
@@ -110,3 +109,12 @@ cmd_attach_session_exec(struct cmd *self, struct cmd_q *cmdq)
 
 	return (CMD_RETURN_NORMAL);
 }
+
+enum cmd_retval
+cmd_attach_session_exec(struct cmd *self, struct cmd_q *cmdq)
+{
+	struct args	*args = self->args;
+
+	return (cmd_attach_session(cmdq, args_get(args, 't'),
+	    args_has(args, 'd'), args_has(args, 'r')));
+}
diff --git a/cmd-new-session.c b/cmd-new-session.c
index 323bc16a..3b1e917f 100644
--- a/cmd-new-session.c
+++ b/cmd-new-session.c
@@ -35,8 +35,8 @@ enum cmd_retval	 cmd_new_session_exec(struct cmd *, struct cmd_q *);
 
 const struct cmd_entry cmd_new_session_entry = {
 	"new-session", "new",
-	"dn:s:t:x:y:", 0, 1,
-	"[-d] [-n window-name] [-s session-name] " CMD_TARGET_SESSION_USAGE
+	"AdDn:s:t:x:y:", 0, 1,
+	"[-AdD] [-n window-name] [-s session-name] " CMD_TARGET_SESSION_USAGE
 	" [-x width] [-y height] [command]",
 	CMD_STARTSERVER|CMD_CANTNEST|CMD_SENDENVIRON,
 	NULL,
@@ -76,6 +76,10 @@ cmd_new_session_exec(struct cmd *self, struct cmd_q *cmdq)
 			return (CMD_RETURN_ERROR);
 		}
 		if (session_find(newname) != NULL) {
+			if (args_has(args, 'A')) {
+				return (cmd_attach_session(cmdq, newname,
+				    args_has(args, 'D'), 0));
+			}
 			cmdq_error(cmdq, "duplicate session: %s", newname);
 			return (CMD_RETURN_ERROR);
 		}
diff --git a/tmux.1 b/tmux.1
index 0f385feb..8e536b67 100644
--- a/tmux.1
+++ b/tmux.1
@@ -670,7 +670,7 @@ command.
 Lock all clients attached to
 .Ar target-session .
 .It Xo Ic new-session
-.Op Fl d
+.Op Fl AdD
 .Op Fl n Ar window-name
 .Op Fl s Ar session-name
 .Op Fl t Ar target-session
@@ -701,6 +701,21 @@ If run from a terminal, any
 .Xr termios 4
 special characters are saved and used for new windows in the new session.
 .Pp
+The
+.Fl A
+flag makes
+.Ic new-session
+behave like
+.Ic attach-session
+if
+.Ar session-name
+already exists; in the case,
+.Fl D
+behaves like
+.Fl d
+to
+.Ic attach-session .
+.Pp
 If
 .Fl t
 is given, the new session is
diff --git a/tmux.h b/tmux.h
index c29e1240..0df1f4d8 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1836,6 +1836,9 @@ extern const struct cmd_entry cmd_unbind_key_entry;
 extern const struct cmd_entry cmd_unlink_window_entry;
 extern const struct cmd_entry cmd_up_pane_entry;
 
+/* cmd-attach-session.c */
+enum cmd_retval	 cmd_attach_session(struct cmd_q *, const char*, int, int);
+
 /* cmd-list.c */
 struct cmd_list	*cmd_list_parse(int, char **, const char *, u_int, char **);
 void		 cmd_list_free(struct cmd_list *);