diff --git a/src/Platform.h b/src/Platform.h
index c502e10b..55a8e9cc 100644
--- a/src/Platform.h
+++ b/src/Platform.h
@@ -32,6 +32,9 @@ void DeInit();
 
 void StopEmu();
 
+// instance ID, for local multiplayer
+int InstanceID();
+
 // configuration values
 
 enum ConfigEntry
diff --git a/src/SPI.cpp b/src/SPI.cpp
index 6ecb86c4..8d15656f 100644
--- a/src/SPI.cpp
+++ b/src/SPI.cpp
@@ -385,24 +385,23 @@ void Reset()
 
     *(u16*)&Firmware[userdata+0x72] = CRC16(&Firmware[userdata], 0x70, 0xFFFF);
 
-    if (firmoverride)
+    //if (firmoverride)
     {
         u8 mac[6];
-        bool rep;
+        bool rep = false;
 
-        if (Platform::GetConfigBool(Platform::Firm_RandomizeMAC))
-        {
-            mac[0] = 0x00;
-            mac[1] = 0x09;
-            mac[2] = 0xBF;
-            mac[3] = rand()&0xFF;
-            mac[4] = rand()&0xFF;
-            mac[5] = rand()&0xFF;
-            rep = true;
-        }
-        else
-        {
+        memcpy(mac, &Firmware[0x36], 6);
+
+        if (firmoverride)
             rep = Platform::GetConfigArray(Platform::Firm_MAC, mac);
+
+        int inst = Platform::InstanceID();
+        if (inst > 0)
+        {
+            rep = true;
+            mac[3] += inst;
+            mac[4] += inst*0x44;
+            mac[5] += inst*0x10;
         }
 
         if (rep)
diff --git a/src/Wifi.cpp b/src/Wifi.cpp
index b69e5632..5b700e76 100644
--- a/src/Wifi.cpp
+++ b/src/Wifi.cpp
@@ -1778,9 +1778,6 @@ u16 Read(u32 addr)
         if (activeread)
         {
             u32 rdaddr = IOPORT(W_RXBufReadAddr);
-
-            //if (*(u16*)&RAM[(rdaddr - 0x1C) & 0x1FFE] == 0x0228)
-            //    printf("READ SHITTY CMD HEADER %08X\n", NDS::GetPC(1));
             u16 ret = *(u16*)&RAM[rdaddr];
 
             rdaddr += 2;
diff --git a/src/frontend/qt_sdl/LocalMP.cpp b/src/frontend/qt_sdl/LocalMP.cpp
index 96ad6e3e..cd6eafb4 100644
--- a/src/frontend/qt_sdl/LocalMP.cpp
+++ b/src/frontend/qt_sdl/LocalMP.cpp
@@ -235,7 +235,7 @@ void SemReset(int num)
 
 bool Init()
 {
-    MPQueue = new QSharedMemory("melonNIFI_FIFO");
+    MPQueue = new QSharedMemory("melonNIFI");
 
     if (!MPQueue->attach())
     {
diff --git a/src/frontend/qt_sdl/Platform.cpp b/src/frontend/qt_sdl/Platform.cpp
index 63f5a147..8f2163ec 100644
--- a/src/frontend/qt_sdl/Platform.cpp
+++ b/src/frontend/qt_sdl/Platform.cpp
@@ -28,6 +28,7 @@
 #include <QSemaphore>
 #include <QMutex>
 #include <QOpenGLContext>
+#include <QSharedMemory>
 
 #include "Platform.h"
 #include "Config.h"
@@ -44,6 +45,55 @@ void emuStop();
 namespace Platform
 {
 
+QSharedMemory* IPCBuffer = nullptr;
+int IPCInstanceID;
+
+void IPCInit()
+{
+    IPCInstanceID = 0;
+
+    IPCBuffer = new QSharedMemory("melonIPC");
+
+    if (!IPCBuffer->attach())
+    {
+        printf("IPC sharedmem doesn't exist. creating\n");
+        if (!IPCBuffer->create(4096))
+        {
+            printf("IPC sharedmem create failed :(\n");
+            delete IPCBuffer;
+            IPCBuffer= nullptr;
+            return;
+        }
+
+        IPCBuffer->lock();
+        memset(IPCBuffer->data(), 0, IPCBuffer->size());
+        IPCBuffer->unlock();
+    }
+
+    IPCBuffer->lock();
+    u8* data = (u8*)IPCBuffer->data();
+    u16 mask = *(u16*)&data[0];
+    for (int i = 0; i < 16; i++)
+    {
+        if (!(mask & (1<<i)))
+        {
+            IPCInstanceID = i;
+            *(u16*)&data[0] |= (1<<i);
+            break;
+        }
+    }
+    IPCBuffer->unlock();
+
+    printf("IPC: instance ID %d\n", IPCInstanceID);
+}
+
+void IPCDeInit()
+{
+    if (IPCBuffer) delete IPCBuffer;
+    IPCBuffer = nullptr;
+}
+
+
 void Init(int argc, char** argv)
 {
 #if defined(__WIN32__) || defined(PORTABLE)
@@ -77,10 +127,13 @@ void Init(int argc, char** argv)
     confdir = config.absolutePath() + "/melonDS/";
     EmuDirectory = confdir.toStdString();
 #endif
+
+    IPCInit();
 }
 
 void DeInit()
 {
+    IPCDeInit();
 }
 
 
@@ -90,6 +143,12 @@ void StopEmu()
 }
 
 
+int InstanceID()
+{
+    return IPCInstanceID;
+}
+
+
 int GetConfigInt(ConfigEntry entry)
 {
     const int imgsizes[] = {0, 256, 512, 1024, 2048, 4096};
diff --git a/src/frontend/qt_sdl/main.cpp b/src/frontend/qt_sdl/main.cpp
index 040e4457..ceb19b5f 100644
--- a/src/frontend/qt_sdl/main.cpp
+++ b/src/frontend/qt_sdl/main.cpp
@@ -647,7 +647,11 @@ void EmuThread::run()
                 if (winUpdateFreq < 1)
                     winUpdateFreq = 1;
 
-                sprintf(melontitle, "[%d/%.0f] melonDS " MELONDS_VERSION, fps, fpstarget);
+                int inst = Platform::InstanceID();
+                if (inst == 0)
+                    sprintf(melontitle, "[%d/%.0f] melonDS " MELONDS_VERSION, fps, fpstarget);
+                else
+                    sprintf(melontitle, "[%d/%.0f] melonDS (%d)", fps, fpstarget, inst+1);
                 changeWindowTitle(melontitle);
             }
         }
@@ -662,7 +666,11 @@ void EmuThread::run()
 
             EmuStatus = EmuRunning;
 
-            sprintf(melontitle, "melonDS " MELONDS_VERSION);
+            int inst = Platform::InstanceID();
+            if (inst == 0)
+                sprintf(melontitle, "melonDS " MELONDS_VERSION);
+            else
+                sprintf(melontitle, "melonDS (%d)", inst+1);
             changeWindowTitle(melontitle);
 
             SDL_Delay(75);