diff --git a/hw/sd.c b/hw/sd.c
index 07eb263..03404a7 100644
--- a/hw/sd.c
+++ b/hw/sd.c
@@ -740,6 +740,9 @@ static sd_rsp_type_t sd_normal_command(SDState *sd,
         break;
 
     case 8:	/* CMD8:   SEND_IF_COND */
+        if (sd->spi) {
+            goto bad_cmd;
+        }
         /* Physical Layer Specification Version 2.00 command */
         switch (sd->state) {
         case sd_idle_state: