diff --git a/components/drivers/sdio/sdio.c b/components/drivers/sdio/sdio.c
index 7b38c39570ae5513b5ba2e248a6e9c8de7dbb058..dc3ddc7e1c908793ec83dc94b785b35861196e65 100644
--- a/components/drivers/sdio/sdio.c
+++ b/components/drivers/sdio/sdio.c
@@ -317,7 +317,7 @@ rt_uint8_t sdio_io_readb(struct rt_sdio_function *func,
                          rt_uint32_t              reg,
                          rt_int32_t              *err)
 {
-    rt_uint8_t data;
+    rt_uint8_t data = 0;
     rt_int32_t ret;
 
     ret = sdio_io_rw_direct(func->card, 0, func->num, reg, &data, 0);