diff -p -up rp-pppoe-3.8/src/configure.in.pppox rp-pppoe-3.8/src/configure.in
--- rp-pppoe-3.8/src/configure.in.pppox	2006-04-02 16:29:42.000000000 +0200
+++ rp-pppoe-3.8/src/configure.in	2008-03-08 00:19:43.000000000 +0100
@@ -25,6 +25,7 @@ AC_CHECK_HEADERS(linux/if_pppox.h, [], [
 #include<sys/socket.h>
 #include<net/ethernet.h>
 #include<linux/if.h>
+#include<linux/in.h>
 ])
 
 dnl Checks for typedefs, structures, and compiler characteristics.
@@ -157,6 +158,7 @@ fi
 AC_TRY_RUN([#include <sys/socket.h>
 #include <net/ethernet.h>
 #include <linux/if.h>
+#include <linux/in.h>
 #include <linux/if_pppox.h>
 int main()
 {