diff --git a/include/wx/longlong.h b/include/wx/longlong.h
index 9b6553ea9a..b6cc42b479 100644
--- a/include/wx/longlong.h
+++ b/include/wx/longlong.h
@@ -411,7 +411,11 @@ public:
     }
 
         // convert to double
+#ifdef _MSC_VER
+    double ToDouble() const { return wx_truncate_cast(double, (__int64) m_ll); }
+#else
     double ToDouble() const { return wx_truncate_cast(double, m_ll); }
+#endif
 
     // operations
         // addition