diff --git a/pkg.m4.in b/pkg.m4.in
index 45427e9..9102bcf 100644
--- a/pkg.m4.in
+++ b/pkg.m4.in
@@ -1,5 +1,5 @@
 # pkg.m4 - Macros to locate and utilise pkg-config.   -*- Autoconf -*-
-# serial 11 (pkg-config-@VERSION@)
+# serial 12 (pkg-config-@VERSION@)
 
 dnl Copyright © 2004 Scott James Remnant <scott@netsplit.com>.
 dnl Copyright © 2012-2015 Dan Nicholson <dbn.lists@gmail.com>