diff --git a/common/main/net_udp.h b/common/main/net_udp.h
index bb14ae3ee..4ed9d2a32 100644
--- a/common/main/net_udp.h
+++ b/common/main/net_udp.h
@@ -37,10 +37,6 @@ void net_udp_send_mdata_direct(const ubyte *data, int data_len, int pnum, int pr
 void net_udp_send_netgame_update();
 
 // Some defines
-#ifdef IPv6
-#define UDP_MCASTv6_ADDR "ff02::1"
-#endif
-#define UDP_BCAST_ADDR "255.255.255.255"
 // Our default port - easy to remember: D = 4, X = 24, X = 24
 const uint16_t UDP_PORT_DEFAULT = 42424;
 #define UDP_MANUAL_ADDR_DEFAULT "localhost"
@@ -51,11 +47,6 @@ const uint16_t UDP_PORT_DEFAULT = 42424;
 #endif
 const uint16_t TRACKER_PORT_DEFAULT = 42420;
 #endif
-#if defined(DXX_BUILD_DESCENT_I)
-#define UDP_REQ_ID "D1XR" // ID string for a request packet
-#elif defined(DXX_BUILD_DESCENT_II)
-#define UDP_REQ_ID "D2XR" // ID string for a request packet
-#endif
 #define UDP_MAX_NETGAMES 900
 #define UDP_NETGAMES_PPAGE 12 // Netgames on one page of Netlist
 #define UDP_NETGAMES_PAGES 75 // Pages available on Netlist (UDP_MAX_NETGAMES/UDP_NETGAMES_PPAGE)
diff --git a/similar/main/net_udp.cpp b/similar/main/net_udp.cpp
index 2f40b8c30..c282e4eaa 100644
--- a/similar/main/net_udp.cpp
+++ b/similar/main/net_udp.cpp
@@ -68,6 +68,12 @@
 #include "highest_valid.h"
 #include "partial_range.h"
 
+#if defined(DXX_BUILD_DESCENT_I)
+#define UDP_REQ_ID "D1XR" // ID string for a request packet
+#elif defined(DXX_BUILD_DESCENT_II)
+#define UDP_REQ_ID "D2XR" // ID string for a request packet
+#endif
+
 // player position packet structure
 struct UDP_frame_info : prohibit_void_ptr<UDP_frame_info>
 {
@@ -122,7 +128,9 @@ static unsigned num_active_udp_games;
 static int num_active_udp_changed;
 static uint16_t UDP_MyPort;
 static sockaddr_in GBcast; // global Broadcast address clients and hosts will use for lite_info exchange over LAN
+#define UDP_BCAST_ADDR "255.255.255.255"
 #ifdef IPv6
+#define UDP_MCASTv6_ADDR "ff02::1"
 static sockaddr_in6 GMcast_v6; // same for IPv6-only
 #define dispatch_sockaddr_from	from.sin6
 #else