diff --git a/language/types/string.xml b/language/types/string.xml
index 7c5de901ea..1df67eb23d 100644
--- a/language/types/string.xml
+++ b/language/types/string.xml
@@ -763,6 +763,15 @@ echo "I'd like an {${beers::$ale}}\n";
     </simpara>
    </warning>
 
+   <warning>
+    <simpara>
+     Internally, PHP strings are byte arrays. As a result, accessing or
+     modifying a string using array brackets is not multi-byte safe, and
+     should only be done with strings that are in a single-byte encoding such
+     as ISO-8859-1.
+    </simpara>
+   </warning>
+
    <example>
     <title>Some string examples</title>
     <programlisting role="php">