diff --git a/language-snippets.ent b/language-snippets.ent
index 3e5dad60ce..255314fd41 100644
--- a/language-snippets.ent
+++ b/language-snippets.ent
@@ -490,7 +490,8 @@ searched for within the <link xmlns="http://docbook.org/ns/docbook" linkend="ini
 
 <!ENTITY return.void 'No value is returned.'>
 
-<!ENTITY return.callbacksort 'The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.'>
+<!ENTITY return.callbacksort 'The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
+Note that before PHP 7.0.0 this integer had to be in the range from -2147483648 to 2147483647.'>
 
 <!ENTITY return.falseproblem '<warning xmlns="http://docbook.org/ns/docbook"><simpara>This function may
 return Boolean &false;, but may also return a non-Boolean value which