diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 4cc9e59270..07c3654b21 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -1217,6 +1217,8 @@ SELECT '52093.89'::money::numeric::float8;
     <type>char(<replaceable>n</replaceable>)</type> are aliases for <type>character
     varying(<replaceable>n</replaceable>)</type> and
     <type>character(<replaceable>n</replaceable>)</type>, respectively.
+    The length specification must be greater than zero and cannot
+    exceed 10485760.
     <type>character</type> without length specifier is equivalent to
     <type>character(1)</type>. If <type>character varying</type> is used
     without length specifier, the type accepts strings of any size. The