diff --git a/include/wx/msw/missing.h b/include/wx/msw/missing.h
index 04ef9d8298..f92d8075df 100644
--- a/include/wx/msw/missing.h
+++ b/include/wx/msw/missing.h
@@ -584,6 +584,14 @@ typedef struct {
     #define WC_NO_BEST_FIT_CHARS 0x400
 #endif
 
+#ifndef OFN_EXPLORER
+    #define OFN_EXPLORER 0x00080000
+#endif
+
+#ifndef OFN_ENABLESIZING
+    #define OFN_ENABLESIZING 0x00800000
+#endif
+
 // In addition, include stuff not defined in WinCE
 #ifdef __WXWINCE__
     #include "wx/msw/wince/missing.h"
diff --git a/src/msw/filedlg.cpp b/src/msw/filedlg.cpp
index 8f72f3e558..7e59525d7b 100644
--- a/src/msw/filedlg.cpp
+++ b/src/msw/filedlg.cpp
@@ -53,9 +53,7 @@
 #include "wx/filename.h"
 #include "wx/tokenzr.h"
 
-#ifndef OFN_EXPLORER
-    #define OFN_EXPLORER 0x00080000
-#endif
+#include "wx/msw/missing.h"
 
 // ----------------------------------------------------------------------------
 // constants