diff --git a/components/dfs/dfs_v1/filesystems/elmfat/dfs_elm.c b/components/dfs/dfs_v1/filesystems/elmfat/dfs_elm.c
index d72b4852fd0..0c9ae7b83ca 100644
--- a/components/dfs/dfs_v1/filesystems/elmfat/dfs_elm.c
+++ b/components/dfs/dfs_v1/filesystems/elmfat/dfs_elm.c
@@ -264,7 +264,7 @@ int dfs_elm_mkfs(rt_device_t dev_id, const char *fs_name)
              * just fill the FatFS[index] in elm fatfs to make mkfs work.
              */
             logic_nbr[0] = '0' + index;
-            f_mount(fat, logic_nbr, (BYTE)index);
+            f_mount(fat, logic_nbr, 0);  /* opt=0: delayed mount, just register FATFS object */
         }
     }
     else
@@ -284,7 +284,7 @@ int dfs_elm_mkfs(rt_device_t dev_id, const char *fs_name)
     /* check flag status, we need clear the temp driver stored in disk[] */
     if (flag == FSM_STATUS_USE_TEMP_DRIVER)
     {
-        f_mount(RT_NULL, logic_nbr, (BYTE)index);
+        f_mount(RT_NULL, logic_nbr, 0);
         rt_free(fat);
         disk[index] = RT_NULL;
         /* close device */
diff --git a/components/dfs/dfs_v2/filesystems/elmfat/dfs_elm.c b/components/dfs/dfs_v2/filesystems/elmfat/dfs_elm.c
index 4d4de5e1230..ac1a4d47e36 100644
--- a/components/dfs/dfs_v2/filesystems/elmfat/dfs_elm.c
+++ b/components/dfs/dfs_v2/filesystems/elmfat/dfs_elm.c
@@ -302,7 +302,7 @@ int dfs_elm_mkfs(rt_device_t dev_id, const char *fs_name)
              * just fill the FatFS[index] in elm fatfs to make mkfs work.
              */
             logic_nbr[0] = '0' + index;
-            f_mount(fat, logic_nbr, (BYTE)index);
+            f_mount(fat, logic_nbr, 0);  /* opt=0: delayed mount, just register FATFS object */
         }
     }
     else
@@ -322,7 +322,7 @@ int dfs_elm_mkfs(rt_device_t dev_id, const char *fs_name)
     /* check flag status, we need clear the temp driver stored in disk[] */
     if (flag == FSM_STATUS_USE_TEMP_DRIVER)
     {
-        f_mount(RT_NULL, logic_nbr, (BYTE)index);
+        f_mount(RT_NULL, logic_nbr, 0);
         rt_free(fat);
         disk[index] = RT_NULL;
         /* close device */