diff --git a/include/exec/memory.h b/include/exec/memory.h
index 2bf5e23..2d7c278 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1837,7 +1837,7 @@
  */
 void memory_region_notify_iommu(IOMMUMemoryRegion *iommu_mr,
                                 int iommu_idx,
-                                IOMMUTLBEvent event);
+                                const IOMMUTLBEvent event);
 
 /**
  * memory_region_notify_iommu_one: notify a change in an IOMMU translation
diff --git a/system/memory.c b/system/memory.c
index f3a37c9..47c600d 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -2052,7 +2052,7 @@
 
 void memory_region_notify_iommu(IOMMUMemoryRegion *iommu_mr,
                                 int iommu_idx,
-                                IOMMUTLBEvent event)
+                                const IOMMUTLBEvent event)
 {
     IOMMUNotifier *iommu_notifier;