diff --git a/reference/array/functions/array-reduce.xml b/reference/array/functions/array-reduce.xml
index 645ce96dc8..ddb167dfa5 100644
--- a/reference/array/functions/array-reduce.xml
+++ b/reference/array/functions/array-reduce.xml
@@ -38,6 +38,11 @@
       <para>
        The callback function.
       </para>
+      <methodsynopsis>
+       <type>void</type><methodname>callback</methodname>
+       <methodparam><type>array</type><parameter role="reference">result</parameter></methodparam>
+       <methodparam><type>mixed</type><parameter>item</parameter></methodparam>
+      </methodsynopsis>
      </listitem>
     </varlistentry>
     <varlistentry>