diff --git a/dlls/ws2_32/socket.c b/dlls/ws2_32/socket.c
index 5b627677954..d688994e629 100644
--- a/dlls/ws2_32/socket.c
+++ b/dlls/ws2_32/socket.c
@@ -761,6 +761,7 @@ static const int ws_proto_map[][2] =
     MAP_OPTION( IPPROTO_ICMP ),
     MAP_OPTION( IPPROTO_IGMP ),
     MAP_OPTION( IPPROTO_RAW ),
+    MAP_OPTION( IPPROTO_IPIP ),
     {FROM_PROTOCOL_INFO, FROM_PROTOCOL_INFO},
 };
 
diff --git a/include/winsock.h b/include/winsock.h
index 891fa9de23b..a8bb35a4c41 100644
--- a/include/winsock.h
+++ b/include/winsock.h
@@ -257,6 +257,7 @@ extern "C" {
 #define IPPROTO_ICMP               1
 #define IPPROTO_IGMP               2
 #define IPPROTO_GGP                3
+#define IPPROTO_IPIP               4
 #define IPPROTO_TCP                6
 #define IPPROTO_UDP                17
 #define IPPROTO_IDP                22
@@ -270,6 +271,7 @@ extern "C" {
 #define WS_IPPROTO_ICMP            1
 #define WS_IPPROTO_IGMP            2
 #define WS_IPPROTO_GGP             3
+#define WS_IPPROTO_IPIP            4
 #define WS_IPPROTO_TCP             6
 #define WS_IPPROTO_UDP             17
 #define WS_IPPROTO_IDP             22