diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index 1e9530f9ae..54bb0ff1c9 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -1669,8 +1669,7 @@ static sd_rsp_type_t sd_app_command(SDState *sd,
     case 22:  /* ACMD22: SEND_NUM_WR_BLOCKS */
         switch (sd->state) {
         case sd_transfer_state:
-            *(uint32_t *) sd->data = sd->blk_written;
-
+            stl_be_p(sd->data, sd->blk_written);
             sd->state = sd_sendingdata_state;
             sd->data_start = 0;
             sd->data_offset = 0;