diff --git a/src/backend/core/Mem.cpp b/src/backend/core/Mem.cpp
index 4a5b2b49..1973f5db 100644
--- a/src/backend/core/Mem.cpp
+++ b/src/backend/core/Mem.cpp
@@ -188,10 +188,11 @@ u8 Mem::Read8(n64::Registers &regs, u32 paddr) {
         return mmio.rdp.rdram[BYTE_ADDRESS(paddr)];
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        if(mirrAddr >= 0x1000) {
-          return mmio.rsp.imem[BYTE_ADDRESS(paddr) & IMEM_DSIZE];
+        if(mirrAddr & 0x1000) {
+          mirrAddr -= 0x1000;
+          return mmio.rsp.imem[BYTE_ADDRESS(mirrAddr)];
         } else {
-          return mmio.rsp.dmem[BYTE_ADDRESS(paddr) & DMEM_DSIZE];
+          return mmio.rsp.dmem[BYTE_ADDRESS(mirrAddr)];
         }
       }
       case 0x04040000 ... 0x040FFFFF:
@@ -257,10 +258,11 @@ u16 Mem::Read16(n64::Registers &regs, u32 paddr) {
         return Util::ReadAccess<u16>(mmio.rdp.rdram, HALF_ADDRESS(paddr));
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        if(mirrAddr >= 0x1000) {
-          return Util::ReadAccess<u16>(mmio.rsp.imem, HALF_ADDRESS(paddr) & IMEM_DSIZE);
+        if(mirrAddr & 0x1000) {
+          mirrAddr -= 0x1000;
+          return Util::ReadAccess<u16>(mmio.rsp.imem, HALF_ADDRESS(mirrAddr));
         } else {
-          return Util::ReadAccess<u16>(mmio.rsp.dmem, HALF_ADDRESS(paddr) & DMEM_DSIZE);
+          return Util::ReadAccess<u16>(mmio.rsp.dmem, HALF_ADDRESS(mirrAddr));
         }
       }
       case MMIO_REGION:
@@ -297,10 +299,11 @@ u32 Mem::Read32(n64::Registers &regs, u32 paddr) {
         return Util::ReadAccess<u32>(mmio.rdp.rdram, paddr);
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        if(mirrAddr >= 0x1000) {
-          return Util::ReadAccess<u32>(mmio.rsp.imem, paddr & IMEM_DSIZE);
+        if(mirrAddr & 0x1000) {
+          mirrAddr -= 0x1000;
+          return Util::ReadAccess<u32>(mmio.rsp.imem, mirrAddr);
         } else {
-          return Util::ReadAccess<u32>(mmio.rsp.dmem, paddr & DMEM_DSIZE);
+          return Util::ReadAccess<u32>(mmio.rsp.dmem, mirrAddr);
         }
       }
       case MMIO_REGION:
@@ -343,10 +346,11 @@ u64 Mem::Read64(n64::Registers &regs, u32 paddr) {
         return Util::ReadAccess<u64>(mmio.rdp.rdram, paddr);
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        if(mirrAddr >= 0x1000) {
-          return Util::ReadAccess<u64>(mmio.rsp.imem, paddr & IMEM_DSIZE);
+        if(mirrAddr & 0x1000) {
+          mirrAddr -= 0x1000;
+          return Util::ReadAccess<u64>(mmio.rsp.imem, mirrAddr);
         } else {
-          return Util::ReadAccess<u64>(mmio.rsp.dmem, paddr & DMEM_DSIZE);
+          return Util::ReadAccess<u64>(mmio.rsp.dmem, mirrAddr);
         }
       }
       case MMIO_REGION:
@@ -383,13 +387,12 @@ void Mem::Write8(Registers& regs, u32 paddr, u32 val) {
         break;
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        val = val << (8 * (3 - (paddr & 3)));
-        if(mirrAddr >= 0x1000) {
-          paddr = (paddr & IMEM_SIZE) & ~3;
-          Util::WriteAccess<u32>(mmio.rsp.imem, paddr & IMEM_DSIZE, val);
+        val = val << (8 * (3 - (mirrAddr & 3)));
+        mirrAddr = (mirrAddr & 0xFFF) & ~3;
+        if(mirrAddr & 0x1000) {
+          Util::WriteAccess<u32>(mmio.rsp.imem, mirrAddr, val);
         } else {
-          paddr = (paddr & DMEM_SIZE) & ~3;
-          Util::WriteAccess<u32>(mmio.rsp.dmem, paddr & DMEM_DSIZE, val);
+          Util::WriteAccess<u32>(mmio.rsp.dmem, mirrAddr, val);
         }
       } break;
       case MMIO_REGION:
@@ -454,13 +457,12 @@ void Mem::Write16(Registers& regs, u32 paddr, u32 val) {
         break;
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        val = val << (16 * !(paddr & 2));
-        if(mirrAddr >= 0x1000) {
-          paddr = (paddr & IMEM_SIZE) & ~3;
-          Util::WriteAccess<u32>(mmio.rsp.imem, paddr & IMEM_DSIZE, val);
+        val = val << (16 * !(mirrAddr & 2));
+        mirrAddr = (mirrAddr & 0xFFF) & ~3;
+        if(mirrAddr & 0x1000) {
+          Util::WriteAccess<u32>(mmio.rsp.imem, mirrAddr, val);
         } else {
-          paddr = (paddr & DMEM_SIZE) & ~3;
-          Util::WriteAccess<u32>(mmio.rsp.dmem, paddr & DMEM_DSIZE, val);
+          Util::WriteAccess<u32>(mmio.rsp.dmem, mirrAddr, val);
         }
       } break;
       case MMIO_REGION:
@@ -504,7 +506,7 @@ void Mem::Write32(Registers& regs, u32 paddr, u32 val) {
         break;
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
-        if(mirrAddr >= 0x1000) {
+        if(mirrAddr & 0x1000) {
           Util::WriteAccess<u32>(mmio.rsp.imem, paddr & IMEM_DSIZE, val);
         } else {
           Util::WriteAccess<u32>(mmio.rsp.dmem, paddr & DMEM_DSIZE, val);
@@ -571,7 +573,7 @@ void Mem::Write64(Registers& regs, u32 paddr, u64 val) {
       case RSP_MEM_REGION: {
         u32 mirrAddr = paddr & 0x1FFF;
         val >>= 32;
-        if(mirrAddr >= 0x1000) {
+        if(mirrAddr & 0x1000) {
           Util::WriteAccess<u32>(mmio.rsp.imem, paddr & IMEM_DSIZE, val);
         } else {
           Util::WriteAccess<u32>(mmio.rsp.dmem, paddr & DMEM_DSIZE, val);