diff --git a/docs/changes.txt b/docs/changes.txt
index e1bf01ebca..9214084c1c 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -240,6 +240,7 @@ All:
 - Fix wx-config generation in CMake builds (Maarten Bent, #22806).
 - Fix compilation of code using wxTransformMatrix with recent gcc (#22790).
 - Fix memory leak when destroying wxThread (Antti Nietosvaara, #22840).
+- Add serial number to wxwin.m4 file (#22848).
 
 All (GUI):
 
diff --git a/wxwin.m4 b/wxwin.m4
index ec0ab09b99..5a0265ea92 100644
--- a/wxwin.m4
+++ b/wxwin.m4
@@ -5,6 +5,9 @@ dnl                  Bob McCown (Mac-testing)
 dnl Creation date:   24/11/2001
 dnl ---------------------------------------------------------------------------
 
+dnl Increment this when changing this file.
+# serial 42
+
 dnl ===========================================================================
 dnl Table of Contents of this macro file:
 dnl -------------------------------------