diff --git a/reference/filesystem/functions/rename.xml b/reference/filesystem/functions/rename.xml
index 66a410bd26..88b9711dfe 100644
--- a/reference/filesystem/functions/rename.xml
+++ b/reference/filesystem/functions/rename.xml
@@ -17,7 +17,10 @@
   <para>
    Attempts to rename <parameter>oldname</parameter> to
    <parameter>newname</parameter>, moving it between directories if necessary.
-   If <parameter>newname</parameter> exists, it will be overwritten.
+   If renaming a file and <parameter>newname</parameter> exists,
+   it will be overwritten. If renaming a directory and
+   <parameter>newname</parameter> exists,
+   this function will emit a warning.
   </para>
  </refsect1>