diff --git a/language/oop5/constants.xml b/language/oop5/constants.xml
index 195938c22e..ff70ad8eee 100644
--- a/language/oop5/constants.xml
+++ b/language/oop5/constants.xml
@@ -22,6 +22,10 @@
   The variable's value can not be a keyword (e.g. <literal>self</literal>,
   <literal>parent</literal> and <literal>static</literal>).
  </para>
+ <para>
+  Note that class constants are allocated once per class, and not for each
+  class instance.
+ </para>
  <example>
   <title>Defining and using a constant</title>
   <programlisting role="php">