diff --git a/gdk/win32/gdkmain-win32.c b/gdk/win32/gdkmain-win32.c
index 4d6e0de648..891a791d6a 100644
--- a/gdk/win32/gdkmain-win32.c
+++ b/gdk/win32/gdkmain-win32.c
@@ -621,6 +621,9 @@ _gdk_win32_window_exstyle_to_string (LONG style)
   BIT (ACCEPTFILES);
   BIT (APPWINDOW);
   BIT (CLIENTEDGE);
+#ifndef WS_EX_COMPOSITED
+#  define WS_EX_COMPOSITED 0x02000000L
+#endif
   BIT (COMPOSITED);
   BIT (CONTEXTHELP);
   BIT (CONTROLPARENT);