diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 7c341c8e3f..fe88c2273a 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -639,7 +639,7 @@ NUMERIC

    <para>
     The <literal>NaN</literal> (not a number) value is used to represent
     undefined [-calculational-]{+computational+} results.  In general, any operation with
     a <literal>NaN</literal> input yields another <literal>NaN</literal>.
     The only exception is when the operation's other inputs are such that
     the same output would be obtained if the <literal>NaN</literal> were to