diff --git a/reference/datetime/dateinterval.xml b/reference/datetime/dateinterval.xml
index 8650467ad7..b1292cf812 100644
--- a/reference/datetime/dateinterval.xml
+++ b/reference/datetime/dateinterval.xml
@@ -168,6 +168,10 @@
        days between the start and end dates. Otherwise,
        <varname>days</varname> will be &false;.
       </para>
+      <para>
+       Before PHP 5.4.20/5.5.4 instead of &false; you will receive -99999 upon
+       accessing the property.
+      </para>
      </listitem>
     </varlistentry>
    </variablelist>