diff --git a/functions/math.xml b/functions/math.xml
index a366474fad..f63237d216 100644
--- a/functions/math.xml
+++ b/functions/math.xml
@@ -264,7 +264,7 @@
      <parameter>frombase</parameter> and <parameter>tobase</parameter>
      have to be between 2 and 36, inclusive.  Digits in numbers with a
      base higher than 10 will be represented with the letters a-z,
-     with a meaning 10, b meaning 11 and z meaning 36.
+     with a meaning 10, b meaning 11 and z meaning 35.
      <example>
       <title><function>Base_convert</function></title>
       <programlisting role="php">