diff --git a/include/WinStd/COM.h b/include/WinStd/COM.h
index 088972ad..0b712b61 100644
--- a/include/WinStd/COM.h
+++ b/include/WinStd/COM.h
@@ -207,7 +207,7 @@ namespace winstd
         bstr(_In_opt_z_ LPCOLESTR src)
         {
             m_h = SysAllocString(src);
-            if (!m_h)
+            if (src && !m_h)
                 throw std::bad_alloc();
         }