diff --git a/README.md b/README.md
index fc91ea0..716c640 100644
--- a/README.md
+++ b/README.md
@@ -105,6 +105,7 @@ docker run -it \
     -p 50922:10022 \
     -v /tmp/.X11-unix:/tmp/.X11-unix \
     -e "DISPLAY=${DISPLAY:-:0.0}" \
+    -e GENERATE_UNIQUE=true \
     sickcodes/docker-osx:auto
 
 # username is user