diff --git a/reference/calendar/functions/jewishtojd.xml b/reference/calendar/functions/jewishtojd.xml
index 534757d022..cee3366186 100644
--- a/reference/calendar/functions/jewishtojd.xml
+++ b/reference/calendar/functions/jewishtojd.xml
@@ -43,7 +43,9 @@
      <term><parameter>day</parameter></term>
      <listitem>
       <para>
-       The day as a number from 1 to 30
+       The day as a number from <literal>1</literal> to <literal>30</literal>.
+       If the month has only 29 days, the first day of the following month is
+       assumed.
       </para>
      </listitem>
     </varlistentry>