diff --git a/functions/strings.sgml b/functions/strings.sgml
index ad3119f586..2f643f860c 100644
--- a/functions/strings.sgml
+++ b/functions/strings.sgml
@@ -1967,7 +1967,7 @@ $rest = substr("abcdef", 1, -1); // returns "bcde"
   </refentry>
 
 
-  <refentry id="substr-replace">
+  <refentry id="function.substr-replace">
    <refnamediv>
 	<refname>substr_replace</refname>
 	<refpurpose>Replace text within a portion of a string.</refpurpose>