diff --git a/sandbox/sandbox.plugin.zsh b/sandbox/sandbox.plugin.zsh
index 1c83367..48c971c 100644
--- a/sandbox/sandbox.plugin.zsh
+++ b/sandbox/sandbox.plugin.zsh
@@ -36,7 +36,7 @@ usage: sandbox [-h] {create,rename,destroy,enable,disable,list} ..
           if [ "$git" = true ]; then
             local repo=$arg
             git=false
-          elif [[ -n "$name" ]]; then
+          elif [[ -z "$name" ]]; then
             error "invalid argument $arg\n$usage" && return 1
           else
             local name=$arg