diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 73f7bfa754..804768d5c6 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -162,6 +162,7 @@ void *qemu_vfio_pci_map_bar(QEMUVFIOState *s, int index,
                             Error **errp)
 {
     void *p;
+    assert(QEMU_IS_ALIGNED(offset, qemu_real_host_page_size));
     assert_bar_index_valid(s, index);
     p = mmap(NULL, MIN(size, s->bar_region_info[index].size - offset),
              prot, MAP_SHARED,