diff --git a/home/user/.tmux/sandbox b/home/user/.tmux/sandbox
index 06fbaee..5c3f75a 100755
--- a/home/user/.tmux/sandbox
+++ b/home/user/.tmux/sandbox
@@ -2,8 +2,17 @@
 
 set -x
 
-readonly RND="${RANDOM}"
-readonly SESSION="sandbox${RND}"
+declare RND="${RANDOM}"
+declare SESSION="sandbox${RND}"
+
+while tmux has-session -t "${SESSION}" 2>/dev/null
+do
+    RND="${RANDOM}"
+    SESSION="sandbox${RND}"
+done
+
+readonly RND
+readonly SESSION
 
 
 declare WORKING_PROJECT