diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 19332296b4e..41b631eb717 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,7 @@
+2004-07-23  Jonathan Wakely  <redi@gcc.gnu.org>
+
+	* docs/html/debug.html: Say debug mode only available since 3.4.0.
+
 2004-07-21  Benjamin Kosnik  <bkoz@redhat.com>
 
 	* docs/doxygen/mainpage.html: Clarify links.
diff --git a/libstdc++-v3/docs/html/debug.html b/libstdc++-v3/docs/html/debug.html
index bfdf38b943f..1bf4bccbaeb 100644
--- a/libstdc++-v3/docs/html/debug.html
+++ b/libstdc++-v3/docs/html/debug.html
@@ -99,7 +99,8 @@
   debug mode that provides additional checking of library facilities,
   and will report errors in the use of libstdc++ as soon as they can
   be detected by emitting a description of the problem to standard
-  error and aborting the program. </p>
+  error and aborting the program.  This debug mode is available with
+  GCC 3.4.0 and later versions. </p>
 
 <p>The libstdc++ debug mode performs checking for many areas of the C++
   standard, but the focus is on checking interactions among standard