diff --git a/include/wx/datetime.h b/include/wx/datetime.h
index 2b88024a5a..d11c669bb1 100644
--- a/include/wx/datetime.h
+++ b/include/wx/datetime.h
@@ -564,7 +564,7 @@ public:
     // ------------------------------------------------------------------------
 
         // default ctor does not initialize the object, use Set()!
-    wxDateTime() { m_time = wxLongLong((long)ULONG_MAX, ULONG_MAX); }
+    wxDateTime() { m_time = wxLongLong(LONG_MIN, 0); }
 
         // from time_t: seconds since the Epoch 00:00:00 UTC, Jan 1, 1970)
 #if (!(defined(__VISAGECPP__) && __IBMCPP__ >= 400))