diff --git a/bin/pt-query-digest b/bin/pt-query-digest
index c8fb121a..30fe2e7c 100755
--- a/bin/pt-query-digest
+++ b/bin/pt-query-digest
@@ -15243,6 +15243,7 @@ A sanity limit for attribute values.
 This option deals with bugs in slow logging functionality that causes large
 values for attributes.  If the attribute's value is bigger than this, the
 last-seen value for that class of query is used instead.
+The default is 4G (2^32). To disable (set no upper limit) set value to 0.
 
 =item --charset