diff -u a/configure.ac b/configure.ac
--- a/configure.ac	2014-09-24 17:39:28.128614303 -0700
+++ b/configure.ac	2014-09-24 17:39:13.748610409 -0700
@@ -470,6 +470,7 @@
 AC_SUBST(SVN_DB_INCLUDES)
 AC_SUBST(SVN_DB_LIBS)
 
+m4_pattern_allow([^AU_])
 SVN_LIB_SASL
 
 if test "$svn_lib_sasl" = "yes"; then