diff --git a/language/functions.xml b/language/functions.xml
index 52b8a5f6fe..4c7d948135 100644
--- a/language/functions.xml
+++ b/language/functions.xml
@@ -154,11 +154,6 @@ Making a cup of espresso.
      The default value must be a constant expression, not (for
      example) a variable or class member.
     </simpara>
-    <para>
-     In PHP 4.0 it's also possible to specify <literal>unset</literal>
-     for default argument.  This means that the argument will not be
-     set at all, if a value is not supplied.
-    </para>
     <para>
      Note that when using default arguments, any defaults should be on
      the right side of any non-default arguments; otherwise, things