diff --git a/reference/reflection/reflectionproperty/getdefaultvalue.xml b/reference/reflection/reflectionproperty/getdefaultvalue.xml
index 887944dc073b..f144016244fc 100644
--- a/reference/reflection/reflectionproperty/getdefaultvalue.xml
+++ b/reference/reflection/reflectionproperty/getdefaultvalue.xml
@@ -30,6 +30,15 @@
    between a &null; default value and an uninitialized typed property.
    Use <methodname>ReflectionProperty::hasDefaultValue</methodname> to detect the difference.
   </simpara>
+  <note>
+   <simpara>
+    For <link linkend="language.oop5.decon.constructor.promotion">promoted properties</link>,
+    the default value is only applied to the constructor parameter, not to the property itself,
+    so this method returns &null; and <methodname>ReflectionProperty::hasDefaultValue</methodname>
+    returns &false;. Use <methodname>ReflectionParameter::getDefaultValue</methodname>
+    on the matching constructor parameter to get it.
+   </simpara>
+  </note>
  </refsect1>
 
  <refsect1 role="changelog">