diff --git a/src/iommu/vfio.c b/src/iommu/vfio.c
index 6f4bea3..f146ebe 100644
--- a/src/iommu/vfio.c
+++ b/src/iommu/vfio.c
@@ -65,7 +65,7 @@ struct vfio_container {
 
 	int fd;
 
-#define VFN_MAX_VFIO_GROUPS 64
+#define VFN_MAX_VFIO_GROUPS 256
 	struct vfio_group groups[VFN_MAX_VFIO_GROUPS];
 	int nr_groups;