diff --git a/htdocs/gcc-15/porting_to.html b/htdocs/gcc-15/porting_to.html
index b9b2efc7..829ae92f 100644
--- a/htdocs/gcc-15/porting_to.html
+++ b/htdocs/gcc-15/porting_to.html
@@ -137,6 +137,12 @@ In file included from <source>:1:
 
 <h2 id="cxx">C++ language issues</h2>
 
+<p>
+Note that all GCC releases make
+<a href="https://gcc.gnu.org/bugs/#upgrading">improvements to conformance</a>
+which may reject non-conforming, legacy codebases.
+</p>
+
 <h3 id="header-dep-changes">Header dependency changes</h3>
 <p>Some C++ Standard Library headers have been changed to no longer include
 other headers that were being used internally by the library.