diff --git a/src/ChatManager.cpp b/src/ChatManager.cpp
index e7db43b..a689ed4 100644
--- a/src/ChatManager.cpp
+++ b/src/ChatManager.cpp
@@ -329,6 +329,7 @@ void instanceCommand(std::string full, std::vector<std::string>& args, CNSocket*
     // no additional arguments: report current instance ID
     if (args.size() < 2) {
         ChatManager::sendServerMessage(sock, "[INST] Current instance ID: " + std::to_string(plr->instanceID));
+        ChatManager::sendServerMessage(sock, "[INST] (Map " + std::to_string(plr->instanceID & 0xffffffff) + ", instance " + std::to_string(plr->instanceID >> 32) + ")");
         return;
     }
 
diff --git a/src/ChunkManager.cpp b/src/ChunkManager.cpp
index 8e80f53..c9c85b7 100644
--- a/src/ChunkManager.cpp
+++ b/src/ChunkManager.cpp
@@ -3,12 +3,12 @@
 #include "NPCManager.hpp"
 #include "settings.hpp"
 
-std::map<std::tuple<int, int, int>, Chunk*> ChunkManager::chunks;
+std::map<std::tuple<int, int, uint64_t>, Chunk*> ChunkManager::chunks;
 
 void ChunkManager::init() {} // stubbed
 
-void ChunkManager::addNPC(int posX, int posY, int instanceID, int32_t id) {
-    std::tuple<int, int, int> pos = grabChunk(posX, posY, instanceID);
+void ChunkManager::addNPC(int posX, int posY, uint64_t instanceID, int32_t id) {
+    std::tuple<int, int, uint64_t> pos = grabChunk(posX, posY, instanceID);
 
     // make chunk if it doesn't exist!
     if (chunks.find(pos) == chunks.end()) {
@@ -22,8 +22,8 @@ void ChunkManager::addNPC(int posX, int posY, int instanceID, int32_t id) {
     chunk->NPCs.insert(id);
 }
 
-void ChunkManager::addPlayer(int posX, int posY, int instanceID, CNSocket* sock) {
-    std::tuple<int, int, int> pos = grabChunk(posX, posY, instanceID);
+void ChunkManager::addPlayer(int posX, int posY, uint64_t instanceID, CNSocket* sock) {
+    std::tuple<int, int, uint64_t> pos = grabChunk(posX, posY, instanceID);
 
     // make chunk if it doesn't exist!
     if (chunks.find(pos) == chunks.end()) {
@@ -37,7 +37,7 @@ void ChunkManager::addPlayer(int posX, int posY, int instanceID, CNSocket* sock)
     chunk->players.insert(sock);
 }
 
-bool ChunkManager::removePlayer(std::tuple<int, int, int> chunkPos, CNSocket* sock) {
+bool ChunkManager::removePlayer(std::tuple<int, int, uint64_t> chunkPos, CNSocket* sock) {
     if (!checkChunk(chunkPos))
         return false; // do nothing if chunk doesn't even exist
 
@@ -57,7 +57,7 @@ bool ChunkManager::removePlayer(std::tuple<int, int, int> chunkPos, CNSocket* so
     return false;
 }
 
-bool ChunkManager::removeNPC(std::tuple<int, int, int> chunkPos, int32_t id) {
+bool ChunkManager::removeNPC(std::tuple<int, int, uint64_t> chunkPos, int32_t id) {
     if (!checkChunk(chunkPos))
         return false; // do nothing if chunk doesn't even exist
 
@@ -77,7 +77,7 @@ bool ChunkManager::removeNPC(std::tuple<int, int, int> chunkPos, int32_t id) {
     return false;
 }
 
-void ChunkManager::destroyChunk(std::tuple<int, int, int> chunkPos) {
+void ChunkManager::destroyChunk(std::tuple<int, int, uint64_t> chunkPos) {
     if (!checkChunk(chunkPos))
         return; // chunk doesn't exist, we don't need to do anything
 
@@ -118,25 +118,26 @@ void ChunkManager::destroyChunk(std::tuple<int, int, int> chunkPos) {
     delete chunk;
 }
 
-bool ChunkManager::checkChunk(std::tuple<int, int, int> chunk) {
+bool ChunkManager::checkChunk(std::tuple<int, int, uint64_t> chunk) {
     return chunks.find(chunk) != chunks.end();
 }
 
-std::tuple<int, int, int> ChunkManager::grabChunk(int posX, int posY, int instanceID) {
+std::tuple<int, int, uint64_t> ChunkManager::grabChunk(int posX, int posY, uint64_t instanceID) {
     return std::make_tuple(posX / (settings::VIEWDISTANCE / 3), posY / (settings::VIEWDISTANCE / 3), instanceID);
 }
 
-std::vector<Chunk*> ChunkManager::grabChunks(std::tuple<int, int, int> chunk) {
+std::vector<Chunk*> ChunkManager::grabChunks(std::tuple<int, int, uint64_t> chunk) {
     std::vector<Chunk*> chnks;
     chnks.reserve(9);
 
-    int x, y, inst;
+    int x, y;
+    uint64_t inst;
     std::tie(x, y, inst) = chunk;
 
     // grabs surrounding chunks if they exist
     for (int i = -1; i < 2; i++) {
         for (int z = -1; z < 2; z++) {
-            std::tuple<int, int, int> pos = std::make_tuple(x+i, y+z, inst);
+            std::tuple<int, int, uint64_t> pos = std::make_tuple(x+i, y+z, inst);
 
             // if chunk exists, add it to the vector
             if (checkChunk(pos))
@@ -170,7 +171,7 @@ std::vector<Chunk*> ChunkManager::getDeltaChunks(std::vector<Chunk*> from, std::
     return delta;
 }
 
-bool ChunkManager::inPopulatedChunks(int posX, int posY, int instanceID) {
+bool ChunkManager::inPopulatedChunks(int posX, int posY, uint64_t instanceID) {
     auto chunk = ChunkManager::grabChunk(posX, posY, instanceID);
     auto nearbyChunks = ChunkManager::grabChunks(chunk);
 
diff --git a/src/ChunkManager.hpp b/src/ChunkManager.hpp
index 633b658..9ba935f 100644
--- a/src/ChunkManager.hpp
+++ b/src/ChunkManager.hpp
@@ -24,16 +24,16 @@ namespace ChunkManager {
     void init();
     void cleanup();
 
-    extern std::map<std::tuple<int, int, int>, Chunk*> chunks;
+    extern std::map<std::tuple<int, int, uint64_t>, Chunk*> chunks;
 
-    void addNPC(int posX, int posY, int instanceID, int32_t id);
-    void addPlayer(int posX, int posY, int instanceID, CNSocket* sock);
-    bool removePlayer(std::tuple<int, int, int> chunkPos, CNSocket* sock);
-    bool removeNPC(std::tuple<int, int, int> chunkPos, int32_t id);
-    bool checkChunk(std::tuple<int, int, int> chunk);
-    void destroyChunk(std::tuple<int, int, int> chunkPos);
-    std::tuple<int, int, int> grabChunk(int posX, int posY, int instanceID);
-    std::vector<Chunk*> grabChunks(std::tuple<int, int, int> chunkPos);
+    void addNPC(int posX, int posY, uint64_t instanceID, int32_t id);
+    void addPlayer(int posX, int posY, uint64_t instanceID, CNSocket* sock);
+    bool removePlayer(std::tuple<int, int, uint64_t> chunkPos, CNSocket* sock);
+    bool removeNPC(std::tuple<int, int, uint64_t> chunkPos, int32_t id);
+    bool checkChunk(std::tuple<int, int, uint64_t> chunk);
+    void destroyChunk(std::tuple<int, int, uint64_t> chunkPos);
+    std::tuple<int, int, uint64_t> grabChunk(int posX, int posY, uint64_t instanceID);
+    std::vector<Chunk*> grabChunks(std::tuple<int, int, uint64_t> chunkPos);
     std::vector<Chunk*> getDeltaChunks(std::vector<Chunk*> from, std::vector<Chunk*> to);
-    bool inPopulatedChunks(int posX, int posY, int instanceID);
+    bool inPopulatedChunks(int posX, int posY, uint64_t instanceID);
 }
diff --git a/src/MobManager.hpp b/src/MobManager.hpp
index 5cb3b9d..ed3f243 100644
--- a/src/MobManager.hpp
+++ b/src/MobManager.hpp
@@ -45,7 +45,7 @@ struct Mob : public BaseNPC {
     // temporary; until we're sure what's what
     nlohmann::json data;
 
-    Mob(int x, int y, int z, int angle, int iID, int type, int hp, nlohmann::json d, int32_t id)
+    Mob(int x, int y, int z, int angle, uint64_t iID, int type, int hp, nlohmann::json d, int32_t id)
         : BaseNPC(x, y, z, angle, iID, type, id), maxHealth(hp) {
         state = MobState::ROAMING;
 
@@ -71,7 +71,7 @@ struct Mob : public BaseNPC {
     }
 
     // constructor for /summon
-    Mob(int x, int y, int z, int iID, int type, nlohmann::json d, int32_t id)
+    Mob(int x, int y, int z, uint64_t iID, int type, nlohmann::json d, int32_t id)
         : Mob(x, y, z, 0, iID, type, 0, d, id) {
         summoned = true; // will be despawned and deallocated when killed
         appearanceData.iHP = maxHealth = d["m_iHP"];
diff --git a/src/NPC.hpp b/src/NPC.hpp
index 724d8de..384fc15 100644
--- a/src/NPC.hpp
+++ b/src/NPC.hpp
@@ -7,12 +7,12 @@ class BaseNPC {
 public:
     sNPCAppearanceData appearanceData;
     NPCClass npcClass;
-    int instanceID;
-    std::tuple<int, int, int> chunkPos;
+    uint64_t instanceID;
+    std::tuple<int, int, uint64_t> chunkPos;
     std::vector<Chunk*> currentChunks;
 
     BaseNPC() {};
-    BaseNPC(int x, int y, int z, int angle, int iID, int type, int id) {
+    BaseNPC(int x, int y, int z, int angle, uint64_t iID, int type, int id) {
         appearanceData.iX = x;
         appearanceData.iY = y;
         appearanceData.iZ = z;
@@ -27,7 +27,7 @@ public:
 
         chunkPos = std::make_tuple(0, 0, instanceID);
     };
-    BaseNPC(int x, int y, int z, int angle, int iID, int type, int id, NPCClass classType) : BaseNPC(x, y, z, angle, iID, type, id) {
+    BaseNPC(int x, int y, int z, int angle, uint64_t iID, int type, int id, NPCClass classType) : BaseNPC(x, y, z, angle, iID, type, id) {
         npcClass = classType;
     }
 };
diff --git a/src/NPCManager.cpp b/src/NPCManager.cpp
index 4dfeac3..2af6426 100644
--- a/src/NPCManager.cpp
+++ b/src/NPCManager.cpp
@@ -146,7 +146,7 @@ void NPCManager::updateNPCPosition(int32_t id, int X, int Y, int Z) {
     npc->appearanceData.iX = X;
     npc->appearanceData.iY = Y;
     npc->appearanceData.iZ = Z;
-    std::tuple<int, int, int> newPos = ChunkManager::grabChunk(X, Y, npc->instanceID);
+    std::tuple<int, int, uint64_t> newPos = ChunkManager::grabChunk(X, Y, npc->instanceID);
 
     // nothing to be done (but we should also update currentChunks to add/remove stale chunks)
     if (newPos == npc->chunkPos) {
@@ -177,7 +177,7 @@ void NPCManager::updateNPCPosition(int32_t id, int X, int Y, int Z) {
     npc->currentChunks = allChunks;
 }
 
-void NPCManager::updateNPCInstance(int32_t npcID, int instanceID) {
+void NPCManager::updateNPCInstance(int32_t npcID, uint64_t instanceID) {
     BaseNPC* npc = NPCs[npcID];
     npc->instanceID = instanceID;
     updateNPCPosition(npcID, npc->appearanceData.iX, npc->appearanceData.iY, npc->appearanceData.iZ);
@@ -591,7 +591,12 @@ void NPCManager::handleWarp(CNSocket* sock, int32_t warpId) {
     // std::cerr << "Warped to Map Num:" << Warps[warpId].instanceID << " NPC ID " << Warps[warpId].npcID << std::endl;
     if (Warps[warpId].isInstance)
     {
-        PlayerManager::sendPlayerTo(sock, Warps[warpId].x, Warps[warpId].y, Warps[warpId].z, Warps[warpId].instanceID);
+        uint64_t instanceID = Warps[warpId].instanceID;
+        if (false) { // TODO check if instance is unique and make a copy
+            instanceID += ((uint64_t)plrv.plr->iIDGroup << 32); // upper 32 bits are leader ID
+        }
+        
+        PlayerManager::sendPlayerTo(sock, Warps[warpId].x, Warps[warpId].y, Warps[warpId].z, instanceID);
     }
     else
     {
@@ -603,7 +608,7 @@ void NPCManager::handleWarp(CNSocket* sock, int32_t warpId) {
         resp.eIL = 4; // do not take away any items
         PlayerManager::removePlayerFromChunks(plrv.currentChunks, sock);
         plrv.currentChunks.clear();
-        plrv.plr->instanceID = 0;
+        plrv.plr->instanceID = INSTANCE_OVERWORLD;
         sock->sendPacket((void*)&resp, P_FE2CL_REP_PC_WARP_USE_NPC_SUCC, sizeof(sP_FE2CL_REP_PC_WARP_USE_NPC_SUCC));
     }
 }
diff --git a/src/NPCManager.hpp b/src/NPCManager.hpp
index 571b0fc..0c99941 100644
--- a/src/NPCManager.hpp
+++ b/src/NPCManager.hpp
@@ -29,7 +29,7 @@ namespace NPCManager {
     void destroyNPC(int32_t);
     void updateNPCPosition(int32_t, int X, int Y, int Z, int angle);
     void updateNPCPosition(int32_t, int X, int Y, int Z);
-    void updateNPCInstance(int32_t, int instanceID);
+    void updateNPCInstance(int32_t, uint64_t instanceID);
 
     void sendToViewable(BaseNPC* npc, void* buf, uint32_t type, size_t size);
 
diff --git a/src/Player.hpp b/src/Player.hpp
index 5499812..a7805ee 100644
--- a/src/Player.hpp
+++ b/src/Player.hpp
@@ -37,7 +37,8 @@ struct Player {
     int32_t iConditionBitFlag;
     int8_t iSpecialState;
 
-    int x, y, z, angle, instanceID;
+    int x, y, z, angle;
+    uint64_t instanceID;
     sItemBase Equip[AEQUIP_COUNT];
     sItemBase Inven[AINVEN_COUNT];
     sItemBase Bank[ABANK_COUNT];
diff --git a/src/PlayerManager.cpp b/src/PlayerManager.cpp
index a20e2f6..fe584ae 100644
--- a/src/PlayerManager.cpp
+++ b/src/PlayerManager.cpp
@@ -194,9 +194,9 @@ void PlayerManager::updatePlayerPosition(CNSocket* sock, int X, int Y, int Z) {
     updatePlayerChunk(sock, X, Y, view.plr->instanceID);
 }
 
-void PlayerManager::updatePlayerChunk(CNSocket* sock, int X, int Y,int mapNum) {
+void PlayerManager::updatePlayerChunk(CNSocket* sock, int X, int Y, uint64_t instanceID) {
     PlayerView& view = players[sock];
-    std::tuple<int, int, int> newPos = ChunkManager::grabChunk(X, Y, view.plr->instanceID);
+    std::tuple<int, int, uint64_t> newPos = ChunkManager::grabChunk(X, Y, view.plr->instanceID);
 
     // nothing to be done
     if (newPos == view.chunkPos)
@@ -222,13 +222,13 @@ void PlayerManager::updatePlayerChunk(CNSocket* sock, int X, int Y,int mapNum) {
     view.currentChunks = allChunks;
 }
 
-void PlayerManager::sendPlayerTo(CNSocket* sock, int X, int Y, int Z, int I) {
+void PlayerManager::sendPlayerTo(CNSocket* sock, int X, int Y, int Z, uint64_t I) {
     PlayerView& plrv = PlayerManager::players[sock];
     Player* plr = plrv.plr;
     plr->instanceID = I;
     if (I != INSTANCE_OVERWORLD) {
         INITSTRUCT(sP_FE2CL_INSTANCE_MAP_INFO, pkt);
-        pkt.iInstanceMapNum = I;
+        pkt.iInstanceMapNum = (int32_t)(I & 0xffffffff); // lower 32 bits are mapnum
         sock->sendPacket((void*)&pkt, P_FE2CL_INSTANCE_MAP_INFO, sizeof(sP_FE2CL_INSTANCE_MAP_INFO));
         sendPlayerTo(sock, X, Y, Z);
     } else {
diff --git a/src/PlayerManager.hpp b/src/PlayerManager.hpp
index f30449c..70f1731 100644
--- a/src/PlayerManager.hpp
+++ b/src/PlayerManager.hpp
@@ -13,7 +13,7 @@
 struct WarpLocation;
 
 struct PlayerView {
-    std::tuple<int, int, int> chunkPos;
+    std::tuple<int, int, uint64_t> chunkPos;
     std::vector<Chunk*> currentChunks;
     Player *plr;
     time_t lastHeartbeat;
@@ -32,9 +32,9 @@ namespace PlayerManager {
 
     void updatePlayerPosition(CNSocket* sock, int X, int Y, int Z);
     void updatePlayerPosition(CNSocket* sock, int X, int Y, int Z, int angle);
-    void updatePlayerChunk(CNSocket* sock, int X, int Y, int instanceID);
+    void updatePlayerChunk(CNSocket* sock, int X, int Y, uint64_t instanceID);
 
-    void sendPlayerTo(CNSocket* sock, int X, int Y, int Z, int I);
+    void sendPlayerTo(CNSocket* sock, int X, int Y, int Z, uint64_t I);
     void sendPlayerTo(CNSocket* sock, int X, int Y, int Z);
 
     void sendToViewable(CNSocket* sock, void* buf, uint32_t type, size_t size);
diff --git a/src/TableData.cpp b/src/TableData.cpp
index 16e35b4..09025db 100644
--- a/src/TableData.cpp
+++ b/src/TableData.cpp
@@ -29,7 +29,7 @@ void TableData::init() {
         inFile >> npcData;
         for (nlohmann::json::iterator _npc = npcData.begin(); _npc != npcData.end(); _npc++) {
             auto npc = _npc.value();
-            int instanceID = npc.find("mapNum") == npc.end() ? INSTANCE_OVERWORLD : (int)npc["mapNum"];
+            uint64_t instanceID = npc.find("mapNum") == npc.end() ? INSTANCE_OVERWORLD : (int)npc["mapNum"];
             BaseNPC *tmp = new BaseNPC(npc["x"], npc["y"], npc["z"], npc["angle"], instanceID, npc["id"], nextId);
 
             NPCManager::NPCs[nextId] = tmp;
@@ -181,7 +181,7 @@ void TableData::init() {
         for (nlohmann::json::iterator _npc = npcData.begin(); _npc != npcData.end(); _npc++) {
             auto npc = _npc.value();
             auto td = NPCManager::NPCData[(int)npc["iNPCType"]];
-            int instanceID = npc.find("iMapNum") == npc.end() ? INSTANCE_OVERWORLD : (int)npc["iMapNum"];
+            uint64_t instanceID = npc.find("iMapNum") == npc.end() ? INSTANCE_OVERWORLD : (int)npc["iMapNum"];
             Mob *tmp = new Mob(npc["iX"], npc["iY"], npc["iZ"], npc["iAngle"], instanceID, npc["iNPCType"], npc["iHP"], td, nextId);
 
             NPCManager::NPCs[nextId] = tmp;
@@ -409,7 +409,7 @@ void TableData::loadGruntwork(int32_t *nextId) {
         auto npcMap = gruntwork["instances"];
         for (auto _map = npcMap.begin(); _map != npcMap.end(); _map++) {
             int32_t npcID = _map.value()["iNPCID"];
-            int instanceID = _map.value()["iMapNum"];
+            uint64_t instanceID = _map.value()["iMapNum"];
             if (NPCManager::NPCs.find(npcID) == NPCManager::NPCs.end())
                 continue; // NPC not found
             BaseNPC* npc = NPCManager::NPCs[npcID];
@@ -423,7 +423,7 @@ void TableData::loadGruntwork(int32_t *nextId) {
         for (auto _mob = mobs.begin(); _mob != mobs.end(); _mob++) {
             auto mob = _mob.value();
 
-            int instanceID = mob.find("iMapNum") == mob.end() ? INSTANCE_OVERWORLD : (int)mob["iMapNum"];
+            uint64_t instanceID = mob.find("iMapNum") == mob.end() ? INSTANCE_OVERWORLD : (int)mob["iMapNum"];
             Mob *npc = new Mob(mob["iX"], mob["iY"], mob["iZ"], instanceID, mob["iNPCType"],
                 NPCManager::NPCData[(int)mob["iNPCType"]], (*nextId)++);