diff --git a/dlls/ntdll/unix/socket.c b/dlls/ntdll/unix/socket.c
index 0269c2b78ae..f33fc014f3b 100644
--- a/dlls/ntdll/unix/socket.c
+++ b/dlls/ntdll/unix/socket.c
@@ -1797,6 +1797,9 @@ NTSTATUS sock_ioctl( HANDLE handle, HANDLE event, PIO_APC_ROUTINE apc, void *apc
 #ifdef IP_UNICAST_IF
         case IOCTL_AFD_WINE_GET_IP_UNICAST_IF:
             return do_getsockopt( handle, io, IPPROTO_IP, IP_UNICAST_IF, out_buffer, out_size );
+
+        case IOCTL_AFD_WINE_SET_IP_UNICAST_IF:
+            return do_setsockopt( handle, io, IPPROTO_IP, IP_UNICAST_IF, in_buffer, in_size );
 #endif
 
         default:
diff --git a/dlls/ws2_32/socket.c b/dlls/ws2_32/socket.c
index f94558520af..d5de709e991 100644
--- a/dlls/ws2_32/socket.c
+++ b/dlls/ws2_32/socket.c
@@ -3705,11 +3705,8 @@ int WINAPI WS_setsockopt(SOCKET s, int level, int optname,
         case WS_IP_UNBLOCK_SOURCE:
             return server_setsockopt( s, IOCTL_AFD_WINE_SET_IP_UNBLOCK_SOURCE, optval, optlen );
 
-#ifdef IP_UNICAST_IF
         case WS_IP_UNICAST_IF:
-#endif
-            convert_sockopt(&level, &optname);
-            break;
+            return server_setsockopt( s, IOCTL_AFD_WINE_SET_IP_UNICAST_IF, optval, optlen );
 
         default:
             FIXME("Unknown IPPROTO_IP optname 0x%08x\n", optname);
diff --git a/include/wine/afd.h b/include/wine/afd.h
index 18e53706fee..c150e2ce474 100644
--- a/include/wine/afd.h
+++ b/include/wine/afd.h
@@ -206,6 +206,7 @@ struct afd_get_events_params
 #define IOCTL_AFD_WINE_SET_IP_TTL                       WINE_AFD_IOC(261)
 #define IOCTL_AFD_WINE_SET_IP_UNBLOCK_SOURCE            WINE_AFD_IOC(262)
 #define IOCTL_AFD_WINE_GET_IP_UNICAST_IF                WINE_AFD_IOC(263)
+#define IOCTL_AFD_WINE_SET_IP_UNICAST_IF                WINE_AFD_IOC(264)
 
 struct afd_create_params
 {