diff --git a/components/fal/src/fal_rtt.c b/components/fal/src/fal_rtt.c
index bfbe66785b..f8d548d9a9 100644
--- a/components/fal/src/fal_rtt.c
+++ b/components/fal/src/fal_rtt.c
@@ -212,7 +212,7 @@ struct fal_mtd_nor_device
     const struct fal_partition     *fal_part;
 };
 
-static rt_ssize_t mtd_nor_dev_read(struct rt_mtd_nor_device* device, rt_off_t offset, rt_uint8_t* data, rt_uint32_t length)
+static rt_ssize_t mtd_nor_dev_read(struct rt_mtd_nor_device* device, rt_off_t offset, rt_uint8_t* data, rt_size_t length)
 {
     int ret = 0;
     struct fal_mtd_nor_device *part = (struct fal_mtd_nor_device*) device;
@@ -233,7 +233,7 @@ static rt_ssize_t mtd_nor_dev_read(struct rt_mtd_nor_device* device, rt_off_t of
     return ret;
 }
 
-static rt_ssize_t mtd_nor_dev_write(struct rt_mtd_nor_device* device, rt_off_t offset, const rt_uint8_t* data, rt_uint32_t length)
+static rt_ssize_t mtd_nor_dev_write(struct rt_mtd_nor_device* device, rt_off_t offset, const rt_uint8_t* data, rt_size_t length)
 {
     int ret = 0;
     struct fal_mtd_nor_device *part;
@@ -255,7 +255,7 @@ static rt_ssize_t mtd_nor_dev_write(struct rt_mtd_nor_device* device, rt_off_t o
     return ret;
 }
 
-static rt_err_t mtd_nor_dev_erase(struct rt_mtd_nor_device* device, rt_off_t offset, rt_uint32_t length)
+static rt_err_t mtd_nor_dev_erase(struct rt_mtd_nor_device* device, rt_off_t offset, rt_size_t length)
 {
     int ret = 0;
     struct fal_mtd_nor_device *part;
@@ -265,7 +265,7 @@ static rt_err_t mtd_nor_dev_erase(struct rt_mtd_nor_device* device, rt_off_t off
 
     ret = fal_partition_erase(part->fal_part, offset, length);
 
-    if ((rt_uint32_t)ret != length || ret < 0)
+    if (ret != (int)length || ret < 0)
     {
         return -RT_ERROR;
     }
@@ -277,10 +277,10 @@ static rt_err_t mtd_nor_dev_erase(struct rt_mtd_nor_device* device, rt_off_t off
 
 static const struct rt_mtd_nor_driver_ops _ops =
 {
-    RT_NULL,
-    mtd_nor_dev_read,
-    mtd_nor_dev_write,
-    mtd_nor_dev_erase,
+    RT_NULL,           /* read_id */
+    mtd_nor_dev_read,  /* read */
+    mtd_nor_dev_write, /* write*/
+    mtd_nor_dev_erase, /* erase_block */
 };
 
 /**