diff --git a/commands/zdiffstore.md b/commands/zdiffstore.md
index d9d2e2cac..be7be22de 100644
--- a/commands/zdiffstore.md
+++ b/commands/zdiffstore.md
@@ -4,7 +4,7 @@ specified by `numkeys`.
 
 Keys that do not exist are considered to be empty sets.
 
-If `destination` already exists, it is overwritten.
+If `destination` already exists, it is overwritten (when the difference is nonempty) or deleted (when the difference is empty)
 
 @examples