diff --git a/wpad_dhcp_posix.c b/wpad_dhcp_posix.c
index db56526..1b8d4d0 100644
--- a/wpad_dhcp_posix.c
+++ b/wpad_dhcp_posix.c
@@ -12,6 +12,7 @@
 #  include <ws2tcpip.h>
 #  include <windows.h>
 #else
+#  include <arpa/inet.h>
 #  include <sys/types.h>
 #  include <sys/socket.h>
 #  include <netdb.h>