diff --git a/include/WinStd/COM.h b/include/WinStd/COM.h
index d7a1e193..7e243d77 100644
--- a/include/WinStd/COM.h
+++ b/include/WinStd/COM.h
@@ -39,6 +39,7 @@ namespace winstd
 
 #pragma once
 
+#include <unknwn.h>
 
 namespace winstd
 {
diff --git a/include/WinStd/Common.h b/include/WinStd/Common.h
index 6152ed4a..00eea5e8 100644
--- a/include/WinStd/Common.h
+++ b/include/WinStd/Common.h
@@ -192,6 +192,12 @@ private:
 #endif
 
 
+#ifndef _LPCBYTE_DEFINED
+#define _LPCBYTE_DEFINED
+typedef const BYTE *LPCBYTE;
+#endif
+
+
 namespace winstd
 {
     /// \addtogroup WinStdStrFormat