diff --git a/reference/strings/functions/substr.xml b/reference/strings/functions/substr.xml
index 4b4a26892f..2eb72c4951 100644
--- a/reference/strings/functions/substr.xml
+++ b/reference/strings/functions/substr.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.3 $ -->
+<!-- $Revision: 1.4 $ -->
 <!-- splitted from ./en/functions/strings.xml, last change in rev 1.2 -->
   <refentry id="function.substr">
    <refnamediv>
@@ -20,7 +20,7 @@
      <parameter>length</parameter> parameters.
     </para>
     <para>
-     If <parameter>start</parameter> is positive, the returned string
+     If <parameter>start</parameter> is non-negative, the returned string
      will start at the <parameter>start</parameter>'th position in
      <parameter>string</parameter>, counting from zero. For instance,
      in the string '<literal>abcdef</literal>', the character at