diff --git a/extmod/fsusermount.c b/extmod/fsusermount.c
index 5882aba991..4ca9b80a60 100644
--- a/extmod/fsusermount.c
+++ b/extmod/fsusermount.c
@@ -32,7 +32,11 @@
 #include "py/nlr.h"
 #include "py/runtime.h"
 #include "py/mperrno.h"
+#if MICROPY_FATFS_OO
+#include "lib/oofatfs/ff.h"
+#else
 #include "lib/fatfs/ff.h"
+#endif
 #include "extmod/fsusermount.h"
 
 fs_user_mount_t *fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args, bool mkfs) {
@@ -57,7 +61,11 @@ fs_user_mount_t *fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp
         for (size_t i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(fs_user_mount)); ++i) {
             fs_user_mount_t *vfs = MP_STATE_PORT(fs_user_mount)[i];
             if (vfs != NULL && !memcmp(mnt_str, vfs->str, mnt_len + 1)) {
+                #if MICROPY_FATFS_OO
+                res = f_umount(&vfs->fatfs);
+                #else
                 res = f_mount(NULL, vfs->str, 0);
+                #endif
                 if (vfs->flags & FSUSER_FREE_OBJ) {
                     m_del_obj(fs_user_mount_t, vfs);
                 }
@@ -86,6 +94,9 @@ fs_user_mount_t *fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp
         vfs->str = mnt_str;
         vfs->len = mnt_len;
         vfs->flags = FSUSER_FREE_OBJ;
+        #if MICROPY_FATFS_OO
+        vfs->fatfs.drv = vfs;
+        #endif
 
         // load block protocol methods
         mp_load_method(device, MP_QSTR_readblocks, vfs->readblocks);
@@ -114,15 +125,30 @@ fs_user_mount_t *fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp
         MP_STATE_PORT(fs_user_mount)[i] = vfs;
 
         // mount the block device (if mkfs, only pre-mount)
-        FRESULT res = f_mount(&vfs->fatfs, vfs->str, !mkfs);
+        FRESULT res;
+        #if MICROPY_FATFS_OO
+        if (mkfs) {
+            res = FR_OK;
+        } else {
+            res = f_mount(&vfs->fatfs);
+        }
+        #else
+        res = f_mount(&vfs->fatfs, vfs->str, !mkfs);
+        #endif
+
         // check the result
         if (res == FR_OK) {
             if (mkfs) {
                 goto mkfs;
             }
         } else if (res == FR_NO_FILESYSTEM && args[1].u_bool) {
-mkfs:
+mkfs:;
+            #if MICROPY_FATFS_OO
+            uint8_t working_buf[_MAX_SS];
+            res = f_mkfs(&vfs->fatfs, FM_FAT | FM_SFD, 0, working_buf, sizeof(working_buf));
+            #else
             res = f_mkfs(vfs->str, 1, 0);
+            #endif
             if (res != FR_OK) {
 mkfs_error:
                 MP_STATE_PORT(fs_user_mount)[i] = NULL;
@@ -130,7 +156,11 @@ mkfs_error:
             }
             if (mkfs) {
                 // If requested to only mkfs, unmount pre-mounted device
+                #if MICROPY_FATFS_OO
+                res = FR_OK;
+                #else
                 res = f_mount(NULL, vfs->str, 0);
+                #endif
                 if (res != FR_OK) {
                     goto mkfs_error;
                 }
@@ -188,7 +218,12 @@ mp_obj_t fatfs_umount(mp_obj_t bdev_or_path_in) {
     }
 
     fs_user_mount_t *vfs = MP_STATE_PORT(fs_user_mount)[i];
-    FRESULT res = f_mount(NULL, vfs->str, 0);
+    FRESULT res;
+    #if MICROPY_FATFS_OO
+    res = f_umount(&vfs->fatfs);
+    #else
+    res = f_mount(NULL, vfs->str, 0);
+    #endif
     if (vfs->flags & FSUSER_FREE_OBJ) {
         m_del_obj(fs_user_mount_t, vfs);
     }
diff --git a/extmod/vfs_fat.c b/extmod/vfs_fat.c
index bd88bcf1b1..36bdb5dbde 100644
--- a/extmod/vfs_fat.c
+++ b/extmod/vfs_fat.c
@@ -28,12 +28,15 @@
 #include "py/mpconfig.h"
 #if MICROPY_VFS_FAT
 
+#if !MICROPY_FATFS_OO
+#error "with MICROPY_VFS_FAT enabled, must also enable MICROPY_FATFS_OO"
+#endif
+
 #include <string.h>
 #include "py/nlr.h"
 #include "py/runtime.h"
 #include "py/mperrno.h"
-#include "lib/fatfs/ff.h"
-#include "lib/fatfs/diskio.h"
+#include "lib/oofatfs/ff.h"
 #include "extmod/vfs_fat_file.h"
 #include "extmod/fsusermount.h"
 #include "timeutils.h"
@@ -55,13 +58,10 @@ STATIC mp_obj_t fat_vfs_mkfs(mp_obj_t bdev_in) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(fat_vfs_mkfs_fun_obj, fat_vfs_mkfs);
 STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(fat_vfs_mkfs_obj, MP_ROM_PTR(&fat_vfs_mkfs_fun_obj));
 
-STATIC mp_obj_t fat_vfs_open(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
-    // Skip self
-    return fatfs_builtin_open(n_args - 1, args + 1, kwargs);
-}
-MP_DEFINE_CONST_FUN_OBJ_KW(fat_vfs_open_obj, 2, fat_vfs_open);
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(fat_vfs_open_obj, 2, fatfs_builtin_open_self);
 
 STATIC mp_obj_t fat_vfs_listdir_func(size_t n_args, const mp_obj_t *args) {
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(args[0]);
     bool is_str_type = true;
     const char *path;
     if (n_args == 2) {
@@ -73,19 +73,16 @@ STATIC mp_obj_t fat_vfs_listdir_func(size_t n_args, const mp_obj_t *args) {
         path = "";
     }
 
-    return fat_vfs_listdir(path, is_str_type);
+    return fat_vfs_listdir2(self, path, is_str_type);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(fat_vfs_listdir_obj, 1, 2, fat_vfs_listdir_func);
 
-STATIC mp_obj_t fat_vfs_remove_internal(mp_obj_t path_in, mp_int_t attr) {
+STATIC mp_obj_t fat_vfs_remove_internal(mp_obj_t vfs_in, mp_obj_t path_in, mp_int_t attr) {
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
     const char *path = mp_obj_str_get_str(path_in);
 
     FILINFO fno;
-#if _USE_LFN
-    fno.lfname = NULL;
-    fno.lfsize = 0;
-#endif
-    FRESULT res = f_stat(path, &fno);
+    FRESULT res = f_stat(&self->fatfs, path, &fno);
 
     if (res != FR_OK) {
         mp_raise_OSError(fresult_to_errno_table[res]);
@@ -93,7 +90,7 @@ STATIC mp_obj_t fat_vfs_remove_internal(mp_obj_t path_in, mp_int_t attr) {
 
     // check if path is a file or directory
     if ((fno.fattrib & AM_DIR) == attr) {
-        res = f_unlink(path);
+        res = f_unlink(&self->fatfs, path);
 
         if (res != FR_OK) {
             mp_raise_OSError(fresult_to_errno_table[res]);
@@ -105,27 +102,25 @@ STATIC mp_obj_t fat_vfs_remove_internal(mp_obj_t path_in, mp_int_t attr) {
 }
 
 STATIC mp_obj_t fat_vfs_remove(mp_obj_t vfs_in, mp_obj_t path_in) {
-    (void)vfs_in;
-    return fat_vfs_remove_internal(path_in, 0); // 0 == file attribute
+    return fat_vfs_remove_internal(vfs_in, path_in, 0); // 0 == file attribute
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_remove_obj, fat_vfs_remove);
 
 STATIC mp_obj_t fat_vfs_rmdir(mp_obj_t vfs_in, mp_obj_t path_in) {
-    (void) vfs_in;
-    return fat_vfs_remove_internal(path_in, AM_DIR);
+    return fat_vfs_remove_internal(vfs_in, path_in, AM_DIR);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_rmdir_obj, fat_vfs_rmdir);
 
 STATIC mp_obj_t fat_vfs_rename(mp_obj_t vfs_in, mp_obj_t path_in, mp_obj_t path_out) {
-    (void)vfs_in;
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
     const char *old_path = mp_obj_str_get_str(path_in);
     const char *new_path = mp_obj_str_get_str(path_out);
-    FRESULT res = f_rename(old_path, new_path);
+    FRESULT res = f_rename(&self->fatfs, old_path, new_path);
     if (res == FR_EXIST) {
         // if new_path exists then try removing it (but only if it's a file)
-        fat_vfs_remove_internal(path_out, 0); // 0 == file attribute
+        fat_vfs_remove_internal(vfs_in, path_out, 0); // 0 == file attribute
         // try to rename again
-        res = f_rename(old_path, new_path);
+        res = f_rename(&self->fatfs, old_path, new_path);
     }
     if (res == FR_OK) {
         return mp_const_none;
@@ -137,9 +132,9 @@ STATIC mp_obj_t fat_vfs_rename(mp_obj_t vfs_in, mp_obj_t path_in, mp_obj_t path_
 STATIC MP_DEFINE_CONST_FUN_OBJ_3(fat_vfs_rename_obj, fat_vfs_rename);
 
 STATIC mp_obj_t fat_vfs_mkdir(mp_obj_t vfs_in, mp_obj_t path_o) {
-    (void)vfs_in;
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
     const char *path = mp_obj_str_get_str(path_o);
-    FRESULT res = f_mkdir(path);
+    FRESULT res = f_mkdir(&self->fatfs, path);
     if (res == FR_OK) {
         return mp_const_none;
     } else {
@@ -150,15 +145,11 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_mkdir_obj, fat_vfs_mkdir);
 
 /// Change current directory.
 STATIC mp_obj_t fat_vfs_chdir(mp_obj_t vfs_in, mp_obj_t path_in) {
-    (void)vfs_in;
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
     const char *path;
     path = mp_obj_str_get_str(path_in);
 
-    FRESULT res = f_chdrive(path);
-
-    if (res == FR_OK) {
-        res = f_chdir(path);
-    }
+    FRESULT res = f_chdir(&self->fatfs, path);
 
     if (res != FR_OK) {
         mp_raise_OSError(fresult_to_errno_table[res]);
@@ -170,14 +161,18 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_chdir_obj, fat_vfs_chdir);
 
 /// Get the current directory.
 STATIC mp_obj_t fat_vfs_getcwd(mp_obj_t vfs_in) {
-    (void)vfs_in;
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
     char buf[MICROPY_ALLOC_PATH_MAX + 1];
-    FRESULT res = f_getcwd(buf, sizeof buf);
-
+    memcpy(buf, self->str, self->len);
+    FRESULT res = f_getcwd(&self->fatfs, buf + self->len, sizeof(buf) - self->len);
     if (res != FR_OK) {
         mp_raise_OSError(fresult_to_errno_table[res]);
     }
-
+    // remove trailing / if in root dir, because we prepended the mount point
+    size_t l = strlen(buf);
+    if (res == FR_OK && buf[l - 1] == '/') {
+        buf[l - 1] = 0;
+    }
     return mp_obj_new_str(buf, strlen(buf), false);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(fat_vfs_getcwd_obj, fat_vfs_getcwd);
@@ -202,14 +197,10 @@ STATIC bool path_equal(const char *path, const char *path_canonical) {
 /// \function stat(path)
 /// Get the status of a file or directory.
 STATIC mp_obj_t fat_vfs_stat(mp_obj_t vfs_in, mp_obj_t path_in) {
-    (void)vfs_in;
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
     const char *path = mp_obj_str_get_str(path_in);
 
     FILINFO fno;
-#if _USE_LFN
-    fno.lfname = NULL;
-    fno.lfsize = 0;
-#endif
     FRESULT res;
 
     if (path_equal(path, "/")) {
@@ -233,7 +224,7 @@ STATIC mp_obj_t fat_vfs_stat(mp_obj_t vfs_in, mp_obj_t path_in) {
         }
         if (res == FR_NO_PATH) {
             // stat normal file
-            res = f_stat(path, &fno);
+            res = f_stat(&self->fatfs, path, &fno);
         }
         if (res != FR_OK) {
             mp_raise_OSError(fresult_to_errno_table[res]);
@@ -272,12 +263,12 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_stat_obj, fat_vfs_stat);
 
 // Get the status of a VFS.
 STATIC mp_obj_t fat_vfs_statvfs(mp_obj_t vfs_in, mp_obj_t path_in) {
-    (void)vfs_in;
-    const char *path = mp_obj_str_get_str(path_in);
+    mp_obj_fat_vfs_t *self = MP_OBJ_TO_PTR(vfs_in);
+    (void)path_in;
 
-    FATFS *fatfs;
     DWORD nclst;
-    FRESULT res = f_getfree(path, &nclst, &fatfs);
+    FATFS *fatfs = &self->fatfs;
+    FRESULT res = f_getfree(fatfs, &nclst);
     if (FR_OK != res) {
         mp_raise_OSError(fresult_to_errno_table[res]);
     }
diff --git a/extmod/vfs_fat_diskio.c b/extmod/vfs_fat_diskio.c
index 3f1902b2e0..9e91b26f7e 100644
--- a/extmod/vfs_fat_diskio.c
+++ b/extmod/vfs_fat_diskio.c
@@ -36,8 +36,13 @@
 #include "py/mphal.h"
 
 #include "py/runtime.h"
+#if MICROPY_FATFS_OO
+#include "lib/oofatfs/ff.h"
+#include "lib/oofatfs/diskio.h"
+#else
 #include "lib/fatfs/ff.h"        /* FatFs lower layer API */
 #include "lib/fatfs/diskio.h"    /* FatFs lower layer API */
+#endif
 #include "extmod/fsusermount.h"
 
 #if _MAX_SS == _MIN_SS
@@ -46,6 +51,13 @@
 #define SECSIZE(fs) ((fs)->ssize)
 #endif
 
+#if MICROPY_FATFS_OO
+typedef void *bdev_t;
+STATIC fs_user_mount_t *disk_get_device(void *bdev) {
+    return (fs_user_mount_t*)bdev;
+}
+#else
+typedef BYTE bdev_t;
 STATIC fs_user_mount_t *disk_get_device(uint id) {
     if (id < MP_ARRAY_SIZE(MP_STATE_PORT(fs_user_mount))) {
         return MP_STATE_PORT(fs_user_mount)[id];
@@ -53,13 +65,17 @@ STATIC fs_user_mount_t *disk_get_device(uint id) {
         return NULL;
     }
 }
+#endif
 
 /*-----------------------------------------------------------------------*/
 /* Initialize a Drive                                                    */
 /*-----------------------------------------------------------------------*/
 
+#if MICROPY_FATFS_OO
+STATIC
+#endif
 DSTATUS disk_initialize (
-    BYTE pdrv                /* Physical drive nmuber (0..) */
+    bdev_t pdrv              /* Physical drive nmuber (0..) */
 )
 {
     fs_user_mount_t *vfs = disk_get_device(pdrv);
@@ -89,8 +105,11 @@ DSTATUS disk_initialize (
 /* Get Disk Status                                                       */
 /*-----------------------------------------------------------------------*/
 
+#if MICROPY_FATFS_OO
+STATIC
+#endif
 DSTATUS disk_status (
-    BYTE pdrv        /* Physical drive nmuber (0..) */
+    bdev_t pdrv      /* Physical drive nmuber (0..) */
 )
 {
     fs_user_mount_t *vfs = disk_get_device(pdrv);
@@ -110,7 +129,7 @@ DSTATUS disk_status (
 /*-----------------------------------------------------------------------*/
 
 DRESULT disk_read (
-    BYTE pdrv,        /* Physical drive nmuber (0..) */
+    bdev_t pdrv,      /* Physical drive nmuber (0..) */
     BYTE *buff,        /* Data buffer to store read data */
     DWORD sector,    /* Sector address (LBA) */
     UINT count        /* Number of sectors to read (1..128) */
@@ -140,9 +159,9 @@ DRESULT disk_read (
 /* Write Sector(s)                                                       */
 /*-----------------------------------------------------------------------*/
 
-#if _USE_WRITE
+#if MICROPY_FATFS_OO || _USE_WRITE
 DRESULT disk_write (
-    BYTE pdrv,            /* Physical drive nmuber (0..) */
+    bdev_t pdrv,          /* Physical drive nmuber (0..) */
     const BYTE *buff,    /* Data to be written */
     DWORD sector,        /* Sector address (LBA) */
     UINT count            /* Number of sectors to write (1..128) */
@@ -179,9 +198,9 @@ DRESULT disk_write (
 /* Miscellaneous Functions                                               */
 /*-----------------------------------------------------------------------*/
 
-#if _USE_IOCTL
+#if MICROPY_FATFS_OO || _USE_IOCTL
 DRESULT disk_ioctl (
-    BYTE pdrv,        /* Physical drive nmuber (0..) */
+    bdev_t pdrv,      /* Physical drive nmuber (0..) */
     BYTE cmd,        /* Control code */
     void *buff        /* Buffer to send/receive control data */
 )
@@ -218,6 +237,10 @@ DRESULT disk_ioctl (
                 } else {
                     *((WORD*)buff) = mp_obj_get_int(ret);
                 }
+                #if MICROPY_FATFS_OO && _MAX_SS != _MIN_SS
+                // need to store ssize because we use it in disk_read/disk_write
+                vfs->fatfs.ssize = *((WORD*)buff);
+                #endif
                 return RES_OK;
             }
 
@@ -225,6 +248,16 @@ DRESULT disk_ioctl (
                 *((DWORD*)buff) = 1; // erase block size in units of sector size
                 return RES_OK;
 
+            #if MICROPY_FATFS_OO
+            case IOCTL_INIT:
+                *((DSTATUS*)buff) = disk_initialize(pdrv);
+                return RES_OK;
+
+            case IOCTL_STATUS:
+                *((DSTATUS*)buff) = disk_status(pdrv);
+                return RES_OK;
+            #endif
+
             default:
                 return RES_PARERR;
         }
@@ -245,12 +278,26 @@ DRESULT disk_ioctl (
 
             case GET_SECTOR_SIZE:
                 *((WORD*)buff) = 512; // old protocol had fixed sector size
+                #if MICROPY_FATFS_OO && _MAX_SS != _MIN_SS
+                // need to store ssize because we use it in disk_read/disk_write
+                vfs->fatfs.ssize = 512;
+                #endif
                 return RES_OK;
 
             case GET_BLOCK_SIZE:
                 *((DWORD*)buff) = 1; // erase block size in units of sector size
                 return RES_OK;
 
+            #if MICROPY_FATFS_OO
+            case IOCTL_INIT:
+                *((DSTATUS*)buff) = disk_initialize(pdrv);
+                return RES_OK;
+
+            case IOCTL_STATUS:
+                *((DSTATUS*)buff) = disk_status(pdrv);
+                return RES_OK;
+            #endif
+
             default:
                 return RES_PARERR;
         }
diff --git a/extmod/vfs_fat_ffconf.c b/extmod/vfs_fat_ffconf.c
index f8935af751..ddcdd88444 100644
--- a/extmod/vfs_fat_ffconf.c
+++ b/extmod/vfs_fat_ffconf.c
@@ -30,10 +30,13 @@
 #include <string.h>
 
 #include "py/mpstate.h"
+#if MICROPY_FATFS_OO
+#include "lib/oofatfs/ff.h"
+#else
 #include "lib/fatfs/ff.h"
-#include "lib/fatfs/ffconf.h"
-#include "lib/fatfs/diskio.h"
+#endif
 #include "extmod/fsusermount.h"
+#include "extmod/vfs_fat_file.h"
 
 STATIC bool check_path(const TCHAR **path, const char *mount_point_str, mp_uint_t mount_point_len) {
     if (strncmp(*path, mount_point_str, mount_point_len) == 0) {
@@ -48,6 +51,37 @@ STATIC bool check_path(const TCHAR **path, const char *mount_point_str, mp_uint_
     return false;
 }
 
+#if MICROPY_FATFS_OO
+
+STATIC fs_user_mount_t *vfs_cur_obj = NULL;
+
+// "path" is the path to lookup; will advance this pointer beyond the volume name.
+// Returns a pointer to the VFS object, NULL means path not found.
+fs_user_mount_t *ff_get_vfs(const char **path) {
+    if (!(*path)) {
+        return NULL;
+    }
+
+    if (**path != '/') {
+        #if _FS_RPATH
+        return vfs_cur_obj;
+        #else
+        return NULL;
+        #endif
+    }
+
+    for (size_t i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(fs_user_mount)); ++i) {
+        fs_user_mount_t *vfs = MP_STATE_PORT(fs_user_mount)[i];
+        if (vfs != NULL && check_path(path, vfs->str, vfs->len)) {
+            return vfs;
+        }
+    }
+
+    return NULL;
+}
+
+#else
+
 // "path" is the path to lookup; will advance this pointer beyond the volume name.
 // Returns logical drive number (-1 means invalid path).
 int ff_get_ldnumber (const TCHAR **path) {
@@ -79,4 +113,6 @@ void ff_get_volname(BYTE vol, TCHAR **dest) {
     *dest += vfs->len;
 }
 
+#endif
+
 #endif // MICROPY_FSUSERMOUNT
diff --git a/extmod/vfs_fat_file.c b/extmod/vfs_fat_file.c
index 77848b5a53..6651d70d05 100644
--- a/extmod/vfs_fat_file.c
+++ b/extmod/vfs_fat_file.c
@@ -36,7 +36,12 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mperrno.h"
+#if MICROPY_FATFS_OO
+#include "lib/oofatfs/ff.h"
+#else
 #include "lib/fatfs/ff.h"
+#endif
+#include "extmod/fsusermount.h"
 #include "extmod/vfs_fat_file.h"
 
 #if MICROPY_VFS_FAT
@@ -112,7 +117,11 @@ STATIC mp_uint_t file_obj_write(mp_obj_t self_in, const void *buf, mp_uint_t siz
 STATIC mp_obj_t file_obj_close(mp_obj_t self_in) {
     pyb_file_obj_t *self = MP_OBJ_TO_PTR(self_in);
     // if fs==NULL then the file is closed and in that case this method is a no-op
+    #if MICROPY_FATFS_OO
+    if (self->fp.obj.fs != NULL) {
+    #else
     if (self->fp.fs != NULL) {
+    #endif
         FRESULT res = f_close(&self->fp);
         if (res != FR_OK) {
             mp_raise_OSError(fresult_to_errno_table[res]);
@@ -178,7 +187,7 @@ STATIC const mp_arg_t file_open_args[] = {
 };
 #define FILE_OPEN_NUM_ARGS MP_ARRAY_SIZE(file_open_args)
 
-STATIC mp_obj_t file_open(const mp_obj_type_t *type, mp_arg_val_t *args) {
+STATIC mp_obj_t file_open(fs_user_mount_t *vfs, const mp_obj_type_t *type, mp_arg_val_t *args) {
     int mode = 0;
     const char *mode_s = mp_obj_str_get_str(args[1].u_obj);
     // TODO make sure only one of r, w, x, a, and b, t are specified
@@ -214,7 +223,19 @@ STATIC mp_obj_t file_open(const mp_obj_type_t *type, mp_arg_val_t *args) {
     o->base.type = type;
 
     const char *fname = mp_obj_str_get_str(args[0].u_obj);
+    #if MICROPY_FATFS_OO
+    if (vfs == NULL) {
+        vfs = ff_get_vfs(&fname);
+        if (vfs == NULL) {
+            m_del_obj(pyb_file_obj_t, o);
+            mp_raise_OSError(MP_ENOENT);
+        }
+    }
+    FRESULT res = f_open(&vfs->fatfs, &o->fp, fname, mode);
+    #else
+    (void)vfs;
     FRESULT res = f_open(&o->fp, fname, mode);
+    #endif
     if (res != FR_OK) {
         m_del_obj(pyb_file_obj_t, o);
         mp_raise_OSError(fresult_to_errno_table[res]);
@@ -231,7 +252,7 @@ STATIC mp_obj_t file_open(const mp_obj_type_t *type, mp_arg_val_t *args) {
 STATIC mp_obj_t file_obj_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_val_t arg_vals[FILE_OPEN_NUM_ARGS];
     mp_arg_parse_all_kw_array(n_args, n_kw, args, FILE_OPEN_NUM_ARGS, file_open_args, arg_vals);
-    return file_open(type, arg_vals);
+    return file_open(NULL, type, arg_vals);
 }
 
 // TODO gc hook to close the file if not already closed
@@ -295,7 +316,16 @@ mp_obj_t fatfs_builtin_open(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw
     // TODO: analyze buffering args and instantiate appropriate type
     mp_arg_val_t arg_vals[FILE_OPEN_NUM_ARGS];
     mp_arg_parse_all(n_args, args, kwargs, FILE_OPEN_NUM_ARGS, file_open_args, arg_vals);
-    return file_open(&mp_type_textio, arg_vals);
+    return file_open(NULL, &mp_type_textio, arg_vals);
+}
+
+// Factory function for I/O stream classes
+mp_obj_t fatfs_builtin_open_self(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
+    // TODO: analyze buffering args and instantiate appropriate type
+    fs_user_mount_t *self = MP_OBJ_TO_PTR(args[0]);
+    mp_arg_val_t arg_vals[FILE_OPEN_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kwargs, FILE_OPEN_NUM_ARGS, file_open_args, arg_vals);
+    return file_open(self, &mp_type_textio, arg_vals);
 }
 
 #endif // MICROPY_FSUSERMOUNT
diff --git a/extmod/vfs_fat_file.h b/extmod/vfs_fat_file.h
index 5c271b6ee6..9693aa04a2 100644
--- a/extmod/vfs_fat_file.h
+++ b/extmod/vfs_fat_file.h
@@ -24,9 +24,15 @@
  * THE SOFTWARE.
  */
 
+struct _fs_user_mount_t;
+
 extern const byte fresult_to_errno_table[20];
 
+struct _fs_user_mount_t *ff_get_vfs(const char **path);
+
 mp_obj_t fatfs_builtin_open(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwargs);
+mp_obj_t fatfs_builtin_open_self(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs);
 MP_DECLARE_CONST_FUN_OBJ_KW(mp_builtin_open_obj);
 
 mp_obj_t fat_vfs_listdir(const char *path, bool is_str_type);
+mp_obj_t fat_vfs_listdir2(struct _fs_user_mount_t *vfs, const char *path, bool is_str_type);
diff --git a/extmod/vfs_fat_misc.c b/extmod/vfs_fat_misc.c
index d3507a85f3..5e89009cd3 100644
--- a/extmod/vfs_fat_misc.c
+++ b/extmod/vfs_fat_misc.c
@@ -32,27 +32,39 @@
 #include <string.h>
 #include "py/nlr.h"
 #include "py/runtime.h"
+#if MICROPY_FATFS_OO
+#include "lib/oofatfs/ff.h"
+#else
 #include "lib/fatfs/ff.h"
-#include "lib/fatfs/diskio.h"
+#endif
 #include "extmod/vfs_fat_file.h"
 #include "extmod/fsusermount.h"
 #include "py/lexer.h"
 
-#if _USE_LFN
+#if !MICROPY_FATFS_OO && _USE_LFN
 STATIC char lfn[_MAX_LFN + 1];   /* Buffer to store the LFN */
 #endif
 
 // TODO: actually, the core function should be ilistdir()
+
 mp_obj_t fat_vfs_listdir(const char *path, bool is_str_type) {
+    return fat_vfs_listdir2(NULL, path, is_str_type);
+}
+
+mp_obj_t fat_vfs_listdir2(fs_user_mount_t *vfs, const char *path, bool is_str_type) {
     FRESULT res;
     FILINFO fno;
     DIR dir;
-#if _USE_LFN
+#if !MICROPY_FATFS_OO && _USE_LFN
     fno.lfname = lfn;
     fno.lfsize = sizeof lfn;
 #endif
 
+    #if MICROPY_FATFS_OO
+    res = f_opendir(&vfs->fatfs, &dir, path);
+    #else
     res = f_opendir(&dir, path);                       /* Open the directory */
+    #endif
     if (res != FR_OK) {
         mp_raise_OSError(fresult_to_errno_table[res]);
     }
@@ -65,7 +77,7 @@ mp_obj_t fat_vfs_listdir(const char *path, bool is_str_type) {
         if (fno.fname[0] == '.' && fno.fname[1] == 0) continue;             /* Ignore . entry */
         if (fno.fname[0] == '.' && fno.fname[1] == '.' && fno.fname[2] == 0) continue;             /* Ignore .. entry */
 
-#if _USE_LFN
+#if !MICROPY_FATFS_OO && _USE_LFN
         char *fn = *fno.lfname ? fno.lfname : fno.fname;
 #else
         char *fn = fno.fname;
@@ -100,11 +112,19 @@ mp_import_stat_t fat_vfs_import_stat(const char *path);
 
 mp_import_stat_t fat_vfs_import_stat(const char *path) {
     FILINFO fno;
-#if _USE_LFN
+#if !MICROPY_FATFS_OO && _USE_LFN
     fno.lfname = NULL;
     fno.lfsize = 0;
 #endif
+    #if MICROPY_FATFS_OO
+    fs_user_mount_t *vfs = ff_get_vfs(&path);
+    if (vfs == NULL) {
+        return MP_IMPORT_STAT_NO_EXIST;
+    }
+    FRESULT res = f_stat(&vfs->fatfs, path, &fno);
+    #else
     FRESULT res = f_stat(path, &fno);
+    #endif
     if (res == FR_OK) {
         if ((fno.fattrib & AM_DIR) != 0) {
             return MP_IMPORT_STAT_DIR;
diff --git a/extmod/vfs_fat_reader.c b/extmod/vfs_fat_reader.c
index 7a00f18de3..efd2de0c16 100644
--- a/extmod/vfs_fat_reader.c
+++ b/extmod/vfs_fat_reader.c
@@ -32,7 +32,12 @@
 
 #if MICROPY_READER_FATFS
 
+#if MICROPY_FATFS_OO
+#include "lib/oofatfs/ff.h"
+#else
 #include "lib/fatfs/ff.h"
+#endif
+#include "extmod/fsusermount.h"
 #include "extmod/vfs_fat_file.h"
 
 typedef struct _mp_reader_fatfs_t {
@@ -71,7 +76,15 @@ int mp_reader_new_file(mp_reader_t *reader, const char *filename) {
     if (rf == NULL) {
         return MP_ENOMEM;
     }
+    #if MICROPY_FATFS_OO
+    fs_user_mount_t *vfs = ff_get_vfs(&filename);
+    if (vfs == NULL) {
+        return MP_ENOENT;
+    }
+    FRESULT res = f_open(&vfs->fatfs, &rf->fp, filename, FA_READ);
+    #else
     FRESULT res = f_open(&rf->fp, filename, FA_READ);
+    #endif
     if (res != FR_OK) {
         return fresult_to_errno_table[res];
     }