diff --git a/README.md b/README.md
index 4e1464c..22cbc9a 100644
--- a/README.md
+++ b/README.md
@@ -5,5 +5,7 @@ Usage:
 ```
 $ bash sd_card_speed_test.sh <path to directory which should be tested>
 ```
+IE: `/Volumes/Untitled` and not `/dev/disk2`
+
 
 Note: administrator password is necessary for sudo to reset file system cache. Read speed result is incorrect without cache reset.