diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index cebc09ef91..7525b5c56e 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -1023,6 +1023,11 @@ CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-tr
    with most but not all server-side encodings.
   </para>
 
+  <para>
+   Another restriction is that PostgreSQL does not support the NUL character
+   (ASCII 0) in character strings, regardless of the character set used.
+  </para>
+
    <sect2 id="multibyte-charset-supported">
     <title>Supported Character Sets</title>