diff --git a/reference/array/functions/array-filter.xml b/reference/array/functions/array-filter.xml
index 00907f1818..a34af7749a 100644
--- a/reference/array/functions/array-filter.xml
+++ b/reference/array/functions/array-filter.xml
@@ -19,7 +19,11 @@
    passing them to the <parameter>callback</parameter> function.
    If the <parameter>callback</parameter> function returns &true;, the
    current value from <parameter>array</parameter> is returned into
-   the result &array;. Array keys are preserved.
+   the result &array;.
+  </para>
+  <para>
+   Array keys are preserved, and may result in gaps if the <parameter>array</parameter> was indexed.
+   The result &array; can be reindexed using the <function>array_values</function> function.
   </para>
 </refsect1>
 
@@ -44,10 +48,9 @@
        The callback function to use
       </para>
       <para>
-       If no <parameter>callback</parameter> is supplied, all entries of
-       <parameter>array</parameter> equal to &false; (see
-       <link linkend="language.types.boolean.casting">converting to
-        boolean</link>) will be removed.
+       If no <parameter>callback</parameter> is supplied, all empty entries of
+       <parameter>array</parameter> will be removed. See <function>empty</function>
+       for how PHP defines empty in this case.
       </para>
      </listitem>
     </varlistentry>