2 files changed, 2 insertions, 2 deletions

diff --git a/src/libs/dutil/WixToolset.DUtil/inc/logutil.h b/src/libs/dutil/WixToolset.DUtil/inc/logutil.h
index 426506ee..1636e297 100644
--- a/src/libs/dutil/WixToolset.DUtil/inc/logutil.h
+++ b/src/libs/dutil/WixToolset.DUtil/inc/logutil.h
@@ -27,7 +27,7 @@ BOOL DAPI IsLogInitialized();
 BOOL DAPI IsLogOpen();
 
 void DAPI LogInitialize(
-    __in HMODULE hModule
+    __in_opt HMODULE hModule
     );
 
 HRESULT DAPI LogOpen(
diff --git a/src/libs/dutil/WixToolset.DUtil/logutil.cpp b/src/libs/dutil/WixToolset.DUtil/logutil.cpp
index ac68036a..bd21098c 100644
--- a/src/libs/dutil/WixToolset.DUtil/logutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/logutil.cpp
@@ -87,7 +87,7 @@ extern "C" BOOL DAPI IsLogOpen()
 
 ********************************************************************/
 extern "C" void DAPI LogInitialize(
-    __in HMODULE hModule
+    __in_opt HMODULE hModule
     )
 {
     AssertSz(INVALID_HANDLE_VALUE == LogUtil_hLog && !LogUtil_sczLogPath, "LogInitialize() or LogOpen() - already called.");