diff --git a/reference/ftp/functions/ftp-rename.xml b/reference/ftp/functions/ftp-rename.xml
index 34ad9c7280..575b071a5b 100644
--- a/reference/ftp/functions/ftp-rename.xml
+++ b/reference/ftp/functions/ftp-rename.xml
@@ -52,7 +52,8 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
-   &return.success;
+   &return.success; Upon failure (such as attempting to rename a non-existent
+   file), an <literal>E_WARNING</literal> error will be emitted.
   </para>
  </refsect1>
  <refsect1 role="examples">