2 files changed, 4 insertions, 4 deletions

diff --git a/src/libs/dutil/WixToolset.DUtil/inc/strutil.h b/src/libs/dutil/WixToolset.DUtil/inc/strutil.h
index f2324a80..6710f599 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/strutil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/strutil.h
@@ -309,10 +309,10 @@ HRESULT DAPI StrSplitAllocArray(
     );
 
 HRESULT DAPI StrSecureZeroString(
-    __in LPWSTR pwz
+    __in_z_opt LPWSTR pwz
     );
 HRESULT DAPI StrSecureZeroFreeString(
-    __in LPWSTR pwz
+    __in_z_opt LPWSTR pwz
     );
 
 #ifdef __cplusplus
diff --git a/src/libs/dutil/WixToolset.DUtil/strutil.cpp b/src/libs/dutil/WixToolset.DUtil/strutil.cpp
index 013c1b12..3c643879 100644
--- a/src/libs/dutil/WixToolset.DUtil/strutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/strutil.cpp
@@ -2774,7 +2774,7 @@ don't remain in memory.
 
 ****************************************************************************/
 extern "C" DAPI_(HRESULT) StrSecureZeroString(
-    __in LPWSTR pwz
+    __in_z_opt LPWSTR pwz
     )
 {
     HRESULT hr = S_OK;
@@ -2798,7 +2798,7 @@ don't remain in memory, then frees the string.
 
 ****************************************************************************/
 extern "C" DAPI_(HRESULT) StrSecureZeroFreeString(
-    __in LPWSTR pwz
+    __in_z_opt LPWSTR pwz
     )
 {
     HRESULT hr = S_OK;