diff --git a/configure.in b/configure.in
index 5ad2b02..982e9d6 100644
--- a/configure.in
+++ b/configure.in
@@ -2,7 +2,7 @@
 AC_INIT(libasn1parser/asn1p_y.y)
 AC_CANONICAL_SYSTEM
 AC_PREREQ(2.53)
-AM_INIT_AUTOMAKE(asn1c, 0.8.12)
+AM_INIT_AUTOMAKE(asn1c, 0.8.13)
 
 AC_SUBST(PATH)
 
@@ -75,6 +75,7 @@
 AC_CHECK_TYPE(intmax_t, int64_t)
 
 AC_CHECK_FUNCS(strtoimax strtoll)
+AC_CHECK_FUNCS(mergesort)
 
 AM_CONFIG_HEADER(config.h)