diff --git a/src/mac/carbon/toplevel.cpp b/src/mac/carbon/toplevel.cpp
index 10b14055bc..51280aecc1 100644
--- a/src/mac/carbon/toplevel.cpp
+++ b/src/mac/carbon/toplevel.cpp
@@ -1174,6 +1174,10 @@ void  wxTopLevelWindowMac::DoMacCreateRealWindow(
         {
             wclass = kDocumentWindowClass ;
         }
+        else if ( HasFlag( wxNO_BORDER ) )
+        {
+            wclass = kSimpleWindowClass ;
+        }
         else
         {
             wclass = kPlainWindowClass ;