diff --git a/reference/datetime/formats.xml b/reference/datetime/formats.xml
index 4a853149dd..891edc8dd0 100644
--- a/reference/datetime/formats.xml
+++ b/reference/datetime/formats.xml
@@ -508,7 +508,7 @@
ii
- [0-5][0-9]
+ [0-5]?[0-9]
"04", "8", "59"
@@ -533,8 +533,8 @@
ss
- [0-5][0-9]
- "04", "8", "59"
+ ([0-5]?[0-9])|60
+ "04", "8", "59", "60" (leap second)
SS