--- configure.ac.orig   2017-01-26 14:27:43.000000000 -0500
+++ configure.ac        2017-11-22 16:11:56.000000000 -0500
@@ -31,7 +31,7 @@
 #endif
 ])
 
-AC_CHECK_DECLS([be32dec, le32dec, be32enc, le32enc, le16dec, le16enc], [], [],
+AC_CHECK_DECLS([be64dec, le64dec, be64enc, le64enc, be32dec, le32dec, be32enc, le32enc, le16dec, le16enc], [], [],
 [AC_INCLUDES_DEFAULT
 #ifdef HAVE_SYS_ENDIAN_H
 #include <sys/endian.h>