Index: utils/GPSsmooth/UGear_main.cxx
--- utils/GPSsmooth/UGear_main.cxx.orig
+++ utils/GPSsmooth/UGear_main.cxx
@@ -4,6 +4,7 @@
 #ifdef HAVE_WINDOWS_H
 #  include <windows.h>
 #else
+#  include <arpa/inet.h>
 #  include <netinet/in.h>       // htonl() ntohl()
 #endif
 
