diff --git a/configure.ac b/configure.ac
index e58f57448..d4a7641eb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,5 @@
 AC_INIT([Pigeonhole], [0.4.11], [dovecot@dovecot.org], [dovecot-2.2-pigeonhole])
-AC_DEFINE_UNQUOTED([PIGEONHOLE_ABI_VERSION], "0.4.ABIv1($PACKAGE_VERSION)", [Pigeonhole ABI version])
+AC_DEFINE_UNQUOTED([PIGEONHOLE_ABI_VERSION], "0.4.ABIv2($PACKAGE_VERSION)", [Pigeonhole ABI version])
 
 AC_CONFIG_AUX_DIR([.])
 AC_CONFIG_SRCDIR([src])