diff --git a/reference/filesystem/functions/flock.xml b/reference/filesystem/functions/flock.xml
index c6996047f3..3b55776dc9 100644
--- a/reference/filesystem/functions/flock.xml
+++ b/reference/filesystem/functions/flock.xml
@@ -164,6 +164,10 @@ fclose($fp);
     <function>fopen</function>).
    </para>
   </note>
+  <warning>
+   Assigning other value to <parameter>handle</parameter> argument in the
+   consecutive code would release the lock.
+  </warning>
   <warning>
    <para>
     <function>flock</function> will not work on NFS and many other networked