diff --git a/reference/errorfunc/functions/error-log.xml b/reference/errorfunc/functions/error-log.xml
index 67425071ec..3eda4d0687 100644
--- a/reference/errorfunc/functions/error-log.xml
+++ b/reference/errorfunc/functions/error-log.xml
@@ -117,6 +117,8 @@
   &reftitle.returnvalues;
   <para>
    &return.success;
+   If <parameter>message_type</parameter> is zero, this function always returns &true;,
+   regardless of whether the error could be logged or not.
   </para>
  </refsect1>