diff --git a/sysdep/autoconf.h.in b/sysdep/autoconf.h.in
index 2827ff49..6cf90aa6 100644
--- a/sysdep/autoconf.h.in
+++ b/sysdep/autoconf.h.in
@@ -37,6 +37,7 @@
 #undef CONFIG_RIP
 #undef CONFIG_BGP
 #undef CONFIG_OSPF
+#undef CONFIG_PIPE
 
 /* We have <syslog.h> and syslog() */
 #undef HAVE_SYSLOG