diff --git a/reference/mbstring/functions/mb-check-encoding.xml b/reference/mbstring/functions/mb-check-encoding.xml
index c4f4d27ebe..ecac4dba94 100644
--- a/reference/mbstring/functions/mb-check-encoding.xml
+++ b/reference/mbstring/functions/mb-check-encoding.xml
@@ -29,8 +29,9 @@
      <term><parameter>var</parameter></term>
      <listitem>
       <para>
-       The byte stream to check. If it is omitted, this function checks
-       all the input from the beginning of the request.
+       The byte stream to check. If it is omitted, this function returns
+       mbstring encoding conversion status. If illegal characters are detected,
+       this function returns &false;, otherwise returns &true;.
       </para>
      </listitem>
     </varlistentry>