diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index cc8e596..c4350e0 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1170,7 +1170,7 @@
     }
 }
 
-typedef int (*vtd_page_walk_hook)(IOMMUTLBEvent *event, void *private);
+typedef int (*vtd_page_walk_hook)(const IOMMUTLBEvent *event, void *private);
 
 /**
  * Constant information used during page walking
@@ -1533,7 +1533,7 @@
     return 0;
 }
 
-static int vtd_sync_shadow_page_hook(IOMMUTLBEvent *event,
+static int vtd_sync_shadow_page_hook(const IOMMUTLBEvent *event,
                                      void *private)
 {
     memory_region_notify_iommu(private, 0, *event);
@@ -2219,7 +2219,7 @@
                  * page tables.  We just deliver the PSI down to
                  * invalidate caches.
                  */
-                IOMMUTLBEvent event = {
+                const IOMMUTLBEvent event = {
                     .type = IOMMU_NOTIFIER_UNMAP,
                     .entry = {
                         .target_as = &address_space_memory,
@@ -3889,7 +3889,7 @@
     vtd_switch_address_space_all(s);
 }
 
-static int vtd_replay_hook(IOMMUTLBEvent *event, void *private)
+static int vtd_replay_hook(const IOMMUTLBEvent *event, void *private)
 {
     memory_region_notify_iommu_one(private, event);
     return 0;