diff --git a/language/operators.xml b/language/operators.xml
index 3d73a0df18..484a054f8f 100644
--- a/language/operators.xml
+++ b/language/operators.xml
@@ -2520,7 +2520,8 @@ bool(false)
    </para>
    <para>
     instanceof does not throw any error if the variable being tested is not
-    an object, it simply returns &false;. Constants, however, are not allowed.
+    an object, it simply returns &false;. Constants, however, were not allowed
+    prior to PHP 7.3.0.
     <example>
      <title>Using <literal>instanceof</literal> to test other variables</title>
      <programlisting role="php">
@@ -2543,6 +2544,26 @@ bool(false)
 bool(false)
 bool(false)
 PHP Fatal error:  instanceof expects an object instance, constant given
+]]>
+     </screen>
+    </example>
+   </para>
+   <para>
+    As of PHP 7.3.0, constants are allowed on the left-hand-side of the
+    <literal>instanceof</literal> operator.
+    <example>
+     <title>Using <literal>instanceof</literal> to test constants</title>
+     <programlisting role="php">
+<![CDATA[
+<?php
+var_dump(FALSE instanceof stdClass);
+?>
+]]>
+    </programlisting>
+    &example.outputs.73;
+    <screen>
+<![CDATA[
+bool(false)
 ]]>
      </screen>
     </example>