===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/tmux/cmd-rename-session.c,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -r1.5 -r1.6
--- src/usr.bin/tmux/cmd-rename-session.c	2009/11/13 19:53:29	1.5
+++ src/usr.bin/tmux/cmd-rename-session.c	2010/08/11 07:45:06	1.6
@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-rename-session.c,v 1.5 2009/11/13 19:53:29 nicm Exp $ */
+/* $OpenBSD: cmd-rename-session.c,v 1.6 2010/08/11 07:45:06 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicm@users.sourceforge.net>
@@ -44,6 +44,11 @@
 {
 	struct cmd_target_data	*data = self->data;
 	struct session		*s;
+
+	if (data->arg != NULL && session_find(data->arg) != NULL) {
+		ctx->error(ctx, "duplicate session: %s", data->arg);
+		return (-1);
+	}
 
 	if ((s = cmd_find_session(ctx, data->target)) == NULL)
 		return (-1);