diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index bc2275c8fe..b2f5a49b29 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1682,6 +1682,10 @@
     </tgroup>
    </table>
 
+   <para>
+    The database must be compiled with ICU in order for contextual aware case-folding,
+    such as word-final characters.
+   </para>
    <para>
     Additional string manipulation functions are available and are
     listed in <xref linkend="functions-string-other"/>.  Some of them are used internally to implement the