--- a/incdefs.sh
+++ b/incdefs.sh
@@ -62,7 +62,7 @@ user_flags()
 kernel_flags()
 {
 	prefix=""
-	tstamp=/usr/include/linux/net_tstamp.h
+	tstamp=/include/uapi/linux/net_tstamp.h
 
 	if [ "x$KBUILD_OUTPUT" != "x" ]; then
 		# With KBUILD_OUTPUT set, we are building against
