diff --git a/source/gamecart/gamecart.c b/source/gamecart/gamecart.c
index 33fed5a..013b236 100644
--- a/source/gamecart/gamecart.c
+++ b/source/gamecart/gamecart.c
@@ -176,7 +176,7 @@ u32 ReadCartSectors(u8* buffer, u32 sector, u32 count, CartData* cdata) {
     return 0;
 }
 
-u32 ReadCartBytes(u8* buffer, u32 offset, u32 count, CartData* cdata) {
+u32 ReadCartBytes(u8* buffer, u64 offset, u64 count, CartData* cdata) {
     if (!(offset % 0x200) && !(count % 0x200)) { // aligned data -> simple case 
         // simple wrapper function for ReadCartSectors(...)
         return ReadCartSectors(buffer, offset / 0x200, count / 0x200, cdata);
@@ -203,7 +203,7 @@ u32 ReadCartBytes(u8* buffer, u32 offset, u32 count, CartData* cdata) {
     }
 }
 
-u32 ReadCartPrivateHeader(u8* buffer, u32 offset, u32 count, CartData* cdata) {
+u32 ReadCartPrivateHeader(u8* buffer, u64 offset, u64 count, CartData* cdata) {
     if (!(cdata->cart_type & CART_CTR)) return 1;
     if (offset < PRIV_HDR_SIZE) {
         u8* priv_hdr = cdata->header + 0x4000;
diff --git a/source/gamecart/gamecart.h b/source/gamecart/gamecart.h
index 653bbb9..9283a34 100644
--- a/source/gamecart/gamecart.h
+++ b/source/gamecart/gamecart.h
@@ -23,5 +23,5 @@ typedef struct {
 u32 GetCartName(char* name, CartData* cdata);
 u32 InitCardRead(CartData* cdata);
 u32 ReadCartSectors(u8* buffer, u32 sector, u32 count, CartData* cdata);
-u32 ReadCartBytes(u8* buffer, u32 offset, u32 count, CartData* cdata);
-u32 ReadCartPrivateHeader(u8* buffer, u32 offset, u32 count, CartData* cdata);
+u32 ReadCartBytes(u8* buffer, u64 offset, u64 count, CartData* cdata);
+u32 ReadCartPrivateHeader(u8* buffer, u64 offset, u64 count, CartData* cdata);
diff --git a/source/nand/nand.c b/source/nand/nand.c
index 015ac23..5af752b 100644
--- a/source/nand/nand.c
+++ b/source/nand/nand.c
@@ -229,7 +229,7 @@ void CryptSector0x96(u8* buffer, bool encrypt)
     ecb_decrypt((void*) buffer, (void*) buffer, 0x200 / AES_BLOCK_SIZE, mode);
 }
 
-int ReadNandBytes(u8* buffer, u32 offset, u32 count, u32 keyslot, u32 nand_src)
+int ReadNandBytes(u8* buffer, u64 offset, u64 count, u32 keyslot, u32 nand_src)
 {
     if (!(offset % 0x200) && !(count % 0x200)) { // aligned data -> simple case 
         // simple wrapper function for ReadNandSectors(...)
@@ -261,7 +261,7 @@ int ReadNandBytes(u8* buffer, u32 offset, u32 count, u32 keyslot, u32 nand_src)
     }
 }
 
-int WriteNandBytes(const u8* buffer, u32 offset, u32 count, u32 keyslot, u32 nand_dst)
+int WriteNandBytes(const u8* buffer, u64 offset, u64 count, u32 keyslot, u32 nand_dst)
 {
     if (!(offset % 0x200) && !(count % 0x200)) { // aligned data -> simple case 
         // simple wrapper function for WriteNandSectors(...)
diff --git a/source/nand/nand.h b/source/nand/nand.h
index 94ad9a4..353c339 100644
--- a/source/nand/nand.h
+++ b/source/nand/nand.h
@@ -41,8 +41,8 @@ bool CheckA9lh(void);
 
 void CryptNand(u8* buffer, u32 sector, u32 count, u32 keyslot);
 void CryptSector0x96(u8* buffer, bool encrypt);
-int ReadNandBytes(u8* buffer, u32 offset, u32 count, u32 keyslot, u32 nand_src);
-int WriteNandBytes(const u8* buffer, u32 offset, u32 count, u32 keyslot, u32 nand_dst);
+int ReadNandBytes(u8* buffer, u64 offset, u64 count, u32 keyslot, u32 nand_src);
+int WriteNandBytes(const u8* buffer, u64 offset, u64 count, u32 keyslot, u32 nand_dst);
 int ReadNandSectors(u8* buffer, u32 sector, u32 count, u32 keyslot, u32 src);
 int WriteNandSectors(const u8* buffer, u32 sector, u32 count, u32 keyslot, u32 dest);
 
diff --git a/source/virtual/vcart.c b/source/virtual/vcart.c
index ad644bb..f0178a4 100644
--- a/source/virtual/vcart.c
+++ b/source/virtual/vcart.c
@@ -53,7 +53,7 @@ bool ReadVCartDir(VirtualFile* vfile, VirtualDir* vdir) {
     return false;
 }
 
-int ReadVCartFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count) {
+int ReadVCartFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count) {
     u32 foffset = vfile->offset + offset;
     if (vfile->flags & VFLAG_PRIV_HDR)
         return ReadCartPrivateHeader(buffer, foffset, count, cdata);
diff --git a/source/virtual/vcart.h b/source/virtual/vcart.h
index 23c5596..4d45272 100644
--- a/source/virtual/vcart.h
+++ b/source/virtual/vcart.h
@@ -5,6 +5,6 @@
 
 u32 InitVCartDrive(void);
 bool ReadVCartDir(VirtualFile* vfile, VirtualDir* vdir);
-int ReadVCartFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count);
-// int WriteVCartFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count); // no writes
+int ReadVCartFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count);
+// int WriteVCartFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count); // no writes
 u64 GetVCartDriveSize(void);
diff --git a/source/virtual/vgame.c b/source/virtual/vgame.c
index a468d21..ca15302 100644
--- a/source/virtual/vgame.c
+++ b/source/virtual/vgame.c
@@ -678,7 +678,7 @@ bool ReadVGameDir(VirtualFile* vfile, VirtualDir* vdir) {
     return false;
 }
 
-int ReadVGameFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count) {
+int ReadVGameFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count) {
     u32 vfoffset = vfile->offset;
     if (vfile->flags & VFLAG_LV3) {
         RomFsLv3FileMeta* lv3file;
diff --git a/source/virtual/vgame.h b/source/virtual/vgame.h
index c1c1e3b..4523800 100644
--- a/source/virtual/vgame.h
+++ b/source/virtual/vgame.h
@@ -9,8 +9,8 @@ u32 CheckVGameDrive(void);
 
 bool OpenVGameDir(VirtualDir* vdir, VirtualFile* ventry);
 bool ReadVGameDir(VirtualFile* vfile, VirtualDir* vdir);
-int ReadVGameFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count);
-// int WriteVGameFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count); // writing is not enabled
+int ReadVGameFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count);
+// int WriteVGameFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count); // writing is not enabled
 
 bool FindVirtualFileInLv3Dir(VirtualFile* vfile, const VirtualDir* vdir, const char* name);
 bool GetVGameLv3Filename(char* name, const VirtualFile* vfile, u32 n_chars);
diff --git a/source/virtual/virtual.c b/source/virtual/virtual.c
index e0062fd..1ca9720 100644
--- a/source/virtual/virtual.c
+++ b/source/virtual/virtual.c
@@ -161,7 +161,7 @@ bool GetVirtualFilename(char* name, const VirtualFile* vfile, u32 n_chars) {
     return true;
 }
 
-int ReadVirtualFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count, u32* bytes_read) {
+int ReadVirtualFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count, u32* bytes_read) {
     // basic check of offset / count
     if (offset >= vfile->size)
         return 0;
@@ -184,7 +184,7 @@ int ReadVirtualFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count,
     return -1;
 }
 
-int WriteVirtualFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count, u32* bytes_written) {
+int WriteVirtualFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count, u32* bytes_written) {
     // basic check of offset / count
     if (offset >= vfile->size)
         return 0;
diff --git a/source/virtual/virtual.h b/source/virtual/virtual.h
index 2bfea00..9a57f50 100644
--- a/source/virtual/virtual.h
+++ b/source/virtual/virtual.h
@@ -57,7 +57,7 @@ bool GetVirtualDirContents(DirStruct* contents, char* fpath, int fnsize, const c
 
 bool GetVirtualFilename(char* name, const VirtualFile* vfile, u32 n_chars);
 
-int ReadVirtualFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count, u32* bytes_read);
-int WriteVirtualFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count, u32* bytes_written);
+int ReadVirtualFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count, u32* bytes_read);
+int WriteVirtualFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count, u32* bytes_written);
 
 u64 GetVirtualDriveSize(const char* path);
diff --git a/source/virtual/vmem.c b/source/virtual/vmem.c
index a8f362a..4a56363 100644
--- a/source/virtual/vmem.c
+++ b/source/virtual/vmem.c
@@ -41,13 +41,13 @@ bool ReadVMemDir(VirtualFile* vfile, VirtualDir* vdir) { // uses a generic vdir
     return false;
 }
 
-int ReadVMemFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count) {
+int ReadVMemFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count) {
     u32 foffset = vfile->offset + offset;
     memcpy(buffer, (u8*) foffset, count);
     return 0;
 }
 
-int WriteVMemFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count) {
+int WriteVMemFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count) {
     u32 foffset = vfile->offset + offset;
     memcpy((u8*) foffset, buffer, count);
     return 0;
diff --git a/source/virtual/vmem.h b/source/virtual/vmem.h
index 706669e..711b12f 100644
--- a/source/virtual/vmem.h
+++ b/source/virtual/vmem.h
@@ -4,5 +4,5 @@
 #include "virtual.h"
 
 bool ReadVMemDir(VirtualFile* vfile, VirtualDir* vdir);
-int ReadVMemFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count);
-int WriteVMemFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count);
+int ReadVMemFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count);
+int WriteVMemFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count);
diff --git a/source/virtual/vnand.c b/source/virtual/vnand.c
index a7e9f18..62f66e5 100644
--- a/source/virtual/vnand.c
+++ b/source/virtual/vnand.c
@@ -88,12 +88,12 @@ bool ReadVNandDir(VirtualFile* vfile, VirtualDir* vdir) { // uses a generic vdir
     return false;
 }
 
-int ReadVNandFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count) {
+int ReadVNandFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count) {
     u32 nand_src = vfile->flags & (VRT_SYSNAND|VRT_EMUNAND|VRT_IMGNAND|VRT_XORPAD);
     return ReadNandBytes(buffer, vfile->offset + offset, count, vfile->keyslot, nand_src);
 }
 
-int WriteVNandFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count) {
+int WriteVNandFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count) {
     u32 nand_dst = vfile->flags & (VRT_SYSNAND|VRT_EMUNAND|VRT_IMGNAND|VRT_XORPAD);
     int res = WriteNandBytes(buffer, vfile->offset + offset, count, vfile->keyslot, nand_dst);
     if ((res == 0) && (vfile->flags & VFLAG_GBA_VC)) res = FixAgbSaveCmac(nand_dst);
diff --git a/source/virtual/vnand.h b/source/virtual/vnand.h
index ae2ac44..8ab2756 100644
--- a/source/virtual/vnand.h
+++ b/source/virtual/vnand.h
@@ -5,6 +5,6 @@
 
 bool CheckVNandDrive(u32 nand_src);
 bool ReadVNandDir(VirtualFile* vfile, VirtualDir* vdir);
-int ReadVNandFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count);
-int WriteVNandFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count);
+int ReadVNandFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count);
+int WriteVNandFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count);
 u64 GetVNandDriveSize(u32 nand_src);
diff --git a/source/virtual/vtickdb.c b/source/virtual/vtickdb.c
index 6676d61..0719c40 100644
--- a/source/virtual/vtickdb.c
+++ b/source/virtual/vtickdb.c
@@ -131,8 +131,8 @@ bool ReadVTickDbDir(VirtualFile* vfile, VirtualDir* vdir) {
     return false;
 }
 
-int ReadVTickDbFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count) {
-    u32 foffset = vfile->offset + offset;
+int ReadVTickDbFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count) {
+    u64 foffset = vfile->offset + offset;
     return (ReadImageBytes(buffer, foffset, count) == 0) ? 0 : 1;
 }
 
diff --git a/source/virtual/vtickdb.h b/source/virtual/vtickdb.h
index 257f07f..f71576a 100644
--- a/source/virtual/vtickdb.h
+++ b/source/virtual/vtickdb.h
@@ -7,6 +7,6 @@ u32 InitVTickDbDrive(void);
 u32 CheckVTickDbDrive(void);
 
 bool ReadVTickDbDir(VirtualFile* vfile, VirtualDir* vdir);
-int ReadVTickDbFile(const VirtualFile* vfile, u8* buffer, u32 offset, u32 count);
-// int WriteVTickDbFile(const VirtualFile* vfile, const u8* buffer, u32 offset, u32 count); // no writing
+int ReadVTickDbFile(const VirtualFile* vfile, u8* buffer, u64 offset, u64 count);
+// int WriteVTickDbFile(const VirtualFile* vfile, const u8* buffer, u64 offset, u64 count); // no writing
 u64 GetVTickDbDriveSize(void);