diff --git a/source/fatfs/image.c b/source/fatfs/image.c
index f14cf82..2bf3c02 100644
--- a/source/fatfs/image.c
+++ b/source/fatfs/image.c
@@ -12,7 +12,7 @@ static u32 mount_state = 0;
 static char mount_path[256] = { 0 };
 
 
-int ReadImageBytes(u8* buffer, u32 offset, u32 count) {
+int ReadImageBytes(u8* buffer, u64 offset, u64 count) {
     UINT bytes_read;
     UINT ret;
     if (!count) return -1;
@@ -30,7 +30,7 @@ int ReadImageBytes(u8* buffer, u32 offset, u32 count) {
     return (ret != 0) ? (int) ret : (bytes_read != count) ? -1 : 0;
 }
 
-int WriteImageBytes(const u8* buffer, u32 offset, u32 count) {
+int WriteImageBytes(const u8* buffer, u64 offset, u64 count) {
     UINT bytes_written;
     UINT ret;
     if (!count) return -1;
diff --git a/source/fatfs/image.h b/source/fatfs/image.h
index 7aad0f8..12af93d 100644
--- a/source/fatfs/image.h
+++ b/source/fatfs/image.h
@@ -5,8 +5,8 @@
 
 #define IMG_RAMDRV 100 // just so there are no conflicts with file type defines
 
-int ReadImageBytes(u8* buffer, u32 offset, u32 count);
-int WriteImageBytes(const u8* buffer, u32 offset, u32 count);
+int ReadImageBytes(u8* buffer, u64 offset, u64 count);
+int WriteImageBytes(const u8* buffer, u64 offset, u64 count);
 int ReadImageSectors(u8* buffer, u32 sector, u32 count);
 int WriteImageSectors(const u8* buffer, u32 sector, u32 count);
 int SyncImage(void);