diff --git a/third_party/rt-thread-5.0/dfs_usbh_msc.c b/third_party/rt-thread-5.0/dfs_usbh_msc.c
index 145bf05d..1d90d636 100644
--- a/third_party/rt-thread-5.0/dfs_usbh_msc.c
+++ b/third_party/rt-thread-5.0/dfs_usbh_msc.c
@@ -51,7 +51,7 @@ static rt_err_t rt_udisk_init(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_ssize_t rt_udisk_read(rt_device_t dev, rt_off_t pos, void *buffer,
+static ssize_t rt_udisk_read(rt_device_t dev, rt_off_t pos, void *buffer,
                                 rt_size_t size)
 {
     struct usbh_msc *msc_class = (struct usbh_msc *)dev->user_data;
@@ -90,7 +90,7 @@ static rt_ssize_t rt_udisk_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return size;
 }
 
-static rt_ssize_t rt_udisk_write(rt_device_t dev, rt_off_t pos, const void *buffer,
+static ssize_t rt_udisk_write(rt_device_t dev, rt_off_t pos, const void *buffer,
                                  rt_size_t size)
 {
     struct usbh_msc *msc_class = (struct usbh_msc *)dev->user_data;