diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index 70200b4eac..461ac68ee8 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -227,6 +227,9 @@ static void virtio_mem_resize_usable_region(VirtIOMEM *vmem,
     uint64_t newsize = MIN(memory_region_size(&vmem->memdev->mr),
                            requested_size + VIRTIO_MEM_USABLE_EXTENT);
 
+    /* The usable region size always has to be multiples of the block size. */
+    newsize = QEMU_ALIGN_UP(newsize, vmem->block_size);
+
     if (!requested_size) {
         newsize = 0;
     }