diff --git a/cs3/storage/provider/v1beta1/resources.proto b/cs3/storage/provider/v1beta1/resources.proto
index c35ffe2d..6fce8a3a 100644
--- a/cs3/storage/provider/v1beta1/resources.proto
+++ b/cs3/storage/provider/v1beta1/resources.proto
@@ -310,6 +310,7 @@ message RecycleItem {
   string key = 3;
   // REQUIRED.
   // The original path of the deleted resource.
+  // MUST start with the slash character (/).
   string path = 4;
   // OPTIONAL.
   // The size of the deleted resource.