diff --git a/reference/filesystem/functions/fwrite.xml b/reference/filesystem/functions/fwrite.xml
index c85ab26f18..5863b8437c 100644
--- a/reference/filesystem/functions/fwrite.xml
+++ b/reference/filesystem/functions/fwrite.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.14 $ -->
+<!-- $Revision: 1.15 $ -->
 <!-- splitted from ./en/functions/filesystem.xml, last change in rev 1.2 -->
 <refentry id="function.fwrite">
  <refnamediv>
@@ -41,6 +41,17 @@
     <function>fopen</function> mode parameter.
    </para>
   </note>
+  <note>
+   <para>
+    If <parameter>handle</parameter> was <function>fopen</function>ed in
+    append mode, <function>fwrite</function>s are atomic (unless the size of
+    <parameter>string</parameter> exceeds the filesystem's block size, on some
+    platforms, and as long as the file is on a local filesystem). That is,
+    there is no need to <function>flock</function> a resource before calling
+    <function>fwrite</function>; all of the data will be written without
+    interruption.
+   </para>
+  </note>
   <para>
    <example>
     <title>A simple <function>fwrite</function> example</title>