diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
index 6811f0f1a8..362c2c86aa 100644
--- a/hw/sd/sdhci.c
+++ b/hw/sd/sdhci.c
@@ -1382,6 +1382,8 @@ void sdhci_initfn(SDHCIState *s)
 
     s->insert_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, sdhci_raise_insertion_irq, s);
     s->transfer_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, sdhci_data_transfer, s);
+
+    s->io_ops = &sdhci_mmio_le_ops;
 }
 
 void sdhci_uninitfn(SDHCIState *s)
@@ -1399,9 +1401,13 @@ void sdhci_common_realize(SDHCIState *s, Error **errp)
 
     switch (s->endianness) {
     case DEVICE_LITTLE_ENDIAN:
-        s->io_ops = &sdhci_mmio_le_ops;
+        /* s->io_ops is little endian by default */
         break;
     case DEVICE_BIG_ENDIAN:
+        if (s->io_ops != &sdhci_mmio_le_ops) {
+            error_setg(errp, "SD controller doesn't support big endianness");
+            return;
+        }
         s->io_ops = &sdhci_mmio_be_ops;
         break;
     default: