diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
index 5564765a9b..40473b0db0 100644
--- a/hw/sd/sdhci.c
+++ b/hw/sd/sdhci.c
@@ -321,6 +321,8 @@ static void sdhci_poweron_reset(DeviceState *dev)
 
 static void sdhci_data_transfer(void *opaque);
 
+#define BLOCK_SIZE_MASK (4 * KiB - 1)
+
 static void sdhci_send_command(SDHCIState *s)
 {
     SDRequest request;
@@ -371,7 +373,8 @@ static void sdhci_send_command(SDHCIState *s)
 
     sdhci_update_irq(s);
 
-    if (!timeout && s->blksize && (s->cmdreg & SDHC_CMD_DATA_PRESENT)) {
+    if (!timeout && (s->blksize & BLOCK_SIZE_MASK) &&
+        (s->cmdreg & SDHC_CMD_DATA_PRESENT)) {
         s->data_count = 0;
         sdhci_data_transfer(s);
     }
@@ -406,7 +409,6 @@ static void sdhci_end_transfer(SDHCIState *s)
 /*
  * Programmed i/o data transfer
  */
-#define BLOCK_SIZE_MASK (4 * KiB - 1)
 
 /* Fill host controller's read buffer with BLKSIZE bytes of data from card */
 static void sdhci_read_block_from_card(SDHCIState *s)
@@ -1154,7 +1156,8 @@ sdhci_write(void *opaque, hwaddr offset, uint64_t val, unsigned size)
             s->sdmasysad = (s->sdmasysad & mask) | value;
             MASKED_WRITE(s->sdmasysad, mask, value);
             /* Writing to last byte of sdmasysad might trigger transfer */
-            if (!(mask & 0xFF000000) && s->blkcnt && s->blksize &&
+            if (!(mask & 0xFF000000) && s->blkcnt &&
+                (s->blksize & BLOCK_SIZE_MASK) &&
                 SDHC_DMA_TYPE(s->hostctl1) == SDHC_CTRL_SDMA) {
                 if (s->trnmod & SDHC_TRNS_MULTI) {
                     sdhci_sdma_transfer_multi_blocks(s);
@@ -1168,7 +1171,11 @@ sdhci_write(void *opaque, hwaddr offset, uint64_t val, unsigned size)
         if (!TRANSFERRING_DATA(s->prnsts)) {
             uint16_t blksize = s->blksize;
 
-            MASKED_WRITE(s->blksize, mask, extract32(value, 0, 12));
+            /*
+             * [14:12] SDMA Buffer Boundary
+             * [11:00] Transfer Block Size
+             */
+            MASKED_WRITE(s->blksize, mask, extract32(value, 0, 15));
             MASKED_WRITE(s->blkcnt, mask >> 16, value >> 16);
 
             /* Limit block size to the maximum buffer size */