diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index 7c9d956f11..805e21fc88 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -807,11 +807,12 @@ static void sd_function_switch(SDState *sd, uint32_t arg)
     sd->data[11] = 0x43;
     sd->data[12] = 0x80;	/* Supported group 1 functions */
     sd->data[13] = 0x03;
+
     for (i = 0; i < 6; i ++) {
         new_func = (arg >> (i * 4)) & 0x0f;
         if (mode && new_func != 0x0f)
             sd->function_group[i] = new_func;
-        sd->data[14 + (i >> 1)] = new_func << ((i * 4) & 4);
+        sd->data[16 - (i >> 1)] |= new_func << ((i % 2) * 4);
     }
     memset(&sd->data[17], 0, 47);
     stw_be_p(sd->data + 64, sd_crc16(sd->data, 64));