diff --git a/features/safe-mode.xml b/features/safe-mode.xml
index 7ab6a61f9c..57cab8ee77 100644
--- a/features/safe-mode.xml
+++ b/features/safe-mode.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.57 $ -->
+<!-- $Revision: 1.58 $ -->
  <chapter id="features.safe-mode">
   <title>Safe Mode</title>
 
@@ -147,6 +147,8 @@
         If PHP is used in safe mode, <function>system</function> and the other
         <link linkend="ref.exec">functions executing system programs</link>
         refuse to start programs that are not in this directory.
+        You have to use <literal>/</literal> as directory separator on all
+        environments including Windows.
        </para>
       </listitem>
      </varlistentry>