diff --git a/reference/reflection/reflectionclass/issubclassof.xml b/reference/reflection/reflectionclass/issubclassof.xml
index 642dc08a47..95e54d1961 100644
--- a/reference/reflection/reflectionclass/issubclassof.xml
+++ b/reference/reflection/reflectionclass/issubclassof.xml
@@ -11,7 +11,7 @@
   &reftitle.description;
   <methodsynopsis>
    <modifier>public</modifier> <type>bool</type><methodname>ReflectionClass::isSubclassOf</methodname>
-   <methodparam><type>string</type><parameter>class</parameter></methodparam>
+   <methodparam><type>mixed</type><parameter>class</parameter></methodparam>
   </methodsynopsis>
   <para>
    Checks if the class is a subclass of a specified class or implements
@@ -27,7 +27,8 @@
      <term><parameter>class</parameter></term>
      <listitem>
       <para>
-       The class name being checked against.
+       Either the name of the class as <type>string</type> or
+       a <type>ReflectionClass</type> object of the class to check against.
       </para>
      </listitem>
     </varlistentry>