diff --git a/reference/filesystem/functions/is-dir.xml b/reference/filesystem/functions/is-dir.xml
index 65cc6dfce9..c350e46931 100644
--- a/reference/filesystem/functions/is-dir.xml
+++ b/reference/filesystem/functions/is-dir.xml
@@ -28,7 +28,9 @@
        Path to the file. If <parameter>filename</parameter> is a relative
        filename, it will be checked relative to the current working
        directory. If <parameter>filename</parameter> is a symbolic or hard link 
-       then the link will be resolved and checked.
+       then the link will be resolved and checked. If you have enabled &safemode;,
+       or <link linkend="ini.open-basedir">open_basedir</link> further
+       restrictions may apply.
       </para>
      </listitem>
     </varlistentry>