diff --git a/tools/ping/README.md b/tools/ping/README.md
index 8c0c513..8df5adc 100644
--- a/tools/ping/README.md
+++ b/tools/ping/README.md
@@ -67,8 +67,10 @@
 one or more printable characters only, to make it easier for a human operator to read the logs.
 A client implementation MAY restrict this field to be non-empty and have printable characters only.
 
-The probe Interest SHOULD carry MustBeFresh selector by default.
-A client implementation MAY allow the operator to turn off MustBeFresh selector.
+The probe Interest SHOULD NOT carry CanBePrefix element.
+
+The probe Interest SHOULD carry MustBeFresh element.
+A client implementation MAY allow the operator to remove MustBeFresh element.
 
 ### Reply Data