diff --git a/kofu.c b/kofu.c
index 2d6e4bb..dbf9fa7 100644
--- a/kofu.c
+++ b/kofu.c
@@ -135,7 +135,7 @@ int main(int argc, char **argv) {
     int fd = open(argv[1], O_RDONLY);
     struct stat st;
     fstat(fd, &st);
-    if (!kos_fuse_init(fd, st.st_size / 512)) {
+    if (!kos_fuse_init(fd, st.st_size / 512, 512)) {
         exit(1);
     }
 
diff --git a/kofuse.c b/kofuse.c
index a8a685d..247d713 100644
--- a/kofuse.c
+++ b/kofuse.c
@@ -102,6 +102,6 @@ int main(int argc, char *argv[]) {
         int fd = open(argv[2], O_RDONLY);
         struct stat st;
         fstat(fd, &st);
-        kos_fuse_init(fd, st.st_size / 512);
+        kos_fuse_init(fd, st.st_size / 512, 512);
         return fuse_main(argc-1, argv, &kofuse_oper, NULL);
 }
diff --git a/kolibri.asm b/kolibri.asm
index d7ce77b..bbd1eba 100644
--- a/kolibri.asm
+++ b/kolibri.asm
@@ -38,7 +38,7 @@ kos_time_to_epoch:
         ret
 
 
-;void *kos_fuse_init(int fd, uint32_t sect_cnt);
+;void *kos_fuse_init(int fd, uint32_t sect_cnt, uint32_t sect_sz);
 public kos_fuse_init
 kos_fuse_init:
         push    ebx esi edi ebp
@@ -49,7 +49,8 @@ kos_fuse_init:
         mov     [file_disk.fd], eax
         mov     eax, [esp + 0x18]
         mov     [file_disk.Sectors], eax
-        mov     [file_disk.Logical], 512
+        mov     eax, [esp + 0x1c]
+        mov     [file_disk.Logical], eax
         stdcall disk_add, disk_functions, disk_name, file_disk, DISK_NO_INSERT_NOTIFICATION
         push    eax
         stdcall disk_media_changed, eax, 1
@@ -75,8 +76,10 @@ proc disk_read stdcall, userdata, buffer, startsector:qword, numsectors
         pushad
         mov     eax, dword[startsector + 0]   ; sector lo
         mov     edx, dword[startsector + 4]   ; sector hi
-        xor     ecx, ecx
-        imul    edx, eax, 512
+        mov     edx, [userdata]
+        mul     [edx + FILE_DISK.Logical]
+        mov     ecx, edx
+        mov     edx, eax
 ;DEBUGF 1, "lseek to: %x\n", edx
         mov     eax, [userdata]
         mov     ebx, [eax + FILE_DISK.fd]
@@ -110,8 +113,10 @@ proc disk_write stdcall, userdata, buffer, startsector:qword, numsectors
         pushad
         mov     eax, dword[startsector + 0]   ; sector lo
         mov     edx, dword[startsector + 4]   ; sector hi
-        xor     ecx, ecx
-        imul    edx, eax, 512
+        mov     edx, [userdata]
+        mul     [edx + FILE_DISK.Logical]
+        mov     ecx, edx
+        mov     edx, eax
 ;DEBUGF 1, "lseek to: %x\n", ecx
         mov     eax, [userdata]
         mov     ebx, [eax + FILE_DISK.fd]
diff --git a/kolibri.h b/kolibri.h
index a873dc8..cf9427d 100644
--- a/kolibri.h
+++ b/kolibri.h
@@ -84,7 +84,7 @@ struct f70s5arg {
 #define KF_FOLDER   0x10
 
 uint32_t kos_time_to_epoch(uint32_t *time);
-void *kos_fuse_init(int fd, uint32_t sect_cnt);
+void *kos_fuse_init(int fd, uint32_t sect_cnt, uint32_t sect_sz);
 int kos_fuse_lfn(void *f70arg);
 
 #endif