diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index f15a47a2f4a..0387b96a658 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -1522,7 +1522,7 @@ SELECT E'\\xDEADBEEF';
        </row>
        <row>
         <entry><type>interval [ <replaceable>fields</replaceable> ] [ (<replaceable>p</replaceable>) ]</type></entry>
-        <entry>12 bytes</entry>
+        <entry>16 bytes</entry>
         <entry>time interval</entry>
         <entry>-178000000 years</entry>
         <entry>178000000 years</entry>