diff --git a/include/WinStd/COM.h b/include/WinStd/COM.h
index f1faacbd..132eab9a 100644
--- a/include/WinStd/COM.h
+++ b/include/WinStd/COM.h
@@ -10,9 +10,10 @@
 
 #include "Common.h"
 #include <assert.h>
-#include <unknwn.h>
+#include <intsafe.h>
 #include <stdexcept>
 #include <string>
+#include <unknwn.h>
 
 namespace winstd
 {
@@ -1507,7 +1508,9 @@ namespace winstd
     ///
     inline _Ret_notnull_ LPSAFEARRAY BuildSAFEARRAY(_In_ VARTYPE vt, _In_opt_ LPCVOID array, _In_ ULONG columns, _In_ ULONG rows)
     {
-        const size_t n = columns * rows;
+        SIZE_T n;
+        if (FAILED(SIZETMult(columns, rows, &n)))
+            throw std::invalid_argument("array is too big");
         if (!array && n)
             throw std::invalid_argument("array is NULL");
 
@@ -1559,7 +1562,9 @@ namespace winstd
     ///
     inline VARIANT BuildVBARRAY(_In_ VARTYPE vt, _In_opt_ LPCVOID array, _In_ ULONG columns, _In_ ULONG rows)
     {
-        const size_t n = columns * rows;
+        SIZE_T n;
+        if (FAILED(SIZETMult(columns, rows, &n)))
+            throw std::invalid_argument("array is too big");
         if (!array && n)
             throw std::invalid_argument("array is NULL");