diff --git a/Doc/Manual/Php.html b/Doc/Manual/Php.html
index fea70a9fa..1ba950c27 100644
--- a/Doc/Manual/Php.html
+++ b/Doc/Manual/Php.html
@@ -271,7 +271,8 @@ if(EASY_TO_MISPEL) {
 <p>
 The mis-spelled constant will become the string 'EASY_TO_MISPEL', which
 is treated as true by the if test, when the value of the intended constant
-would be treated as false!
+would be treated as false!  Modern versions of PHP will at least issue
+a PHP notice by default when this happens.
 </p>
 
 <H3><a name="Php_nn2_2">34.2.2 Global Variables</a></H3>