diff --git a/reference/intl/idn/idn-to-ascii.xml b/reference/intl/idn/idn-to-ascii.xml
index 40b1fd5ea8..9a8c2a48e6 100644
--- a/reference/intl/idn/idn-to-ascii.xml
+++ b/reference/intl/idn/idn-to-ascii.xml
@@ -45,8 +45,8 @@
      <term><parameter>variant</parameter></term>
      <listitem>
       <para>
-       Either <constant>INTL_IDNA_VARIANT_2003</constant> for IDNA 2003 or
-       <constant>INTL_IDNA_VARIANT_UTS46</constant> for UTS #46.
+       Either <constant>INTL_IDNA_VARIANT_2003</constant> (deprecated as of PHP 7.2.0) for IDNA 2003 or
+       <constant>INTL_IDNA_VARIANT_UTS46</constant> (only available as of ICU 4.6) for UTS #46.
       </para>
      </listitem>
     </varlistentry>
diff --git a/reference/intl/idn/idn-to-utf8.xml b/reference/intl/idn/idn-to-utf8.xml
index 7bb6976feb..64789d5b08 100644
--- a/reference/intl/idn/idn-to-utf8.xml
+++ b/reference/intl/idn/idn-to-utf8.xml
@@ -45,8 +45,8 @@
      <term><parameter>variant</parameter></term>
      <listitem>
       <para>
-       Either <constant>INTL_IDNA_VARIANT_2003</constant> for IDNA 2003 or
-       <constant>INTL_IDNA_VARIANT_UTS46</constant> for UTS #46.
+       Either <constant>INTL_IDNA_VARIANT_2003</constant> (deprecated as of PHP 7.2.0) for IDNA 2003 or
+       <constant>INTL_IDNA_VARIANT_UTS46</constant> (only available as of ICU 4.6) for UTS #46.
       </para>
      </listitem>
     </varlistentry>