diff --git a/Makefile.am b/Makefile.am
index b5aeb45c..4727ffd4 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,5 +1,5 @@
 ## Process this file with automake to produce Makefile.in -*-Makefile-*-
-AUTOMAKE_OPTIONS = 1.4
+AUTOMAKE_OPTIONS = 1.4 ansi2knr
 
 bin_PROGRAMS = bison