diff --git a/cde/programs/dtmail/include/MotifApp/Application.h b/cde/programs/dtmail/include/MotifApp/Application.h
index 9f832b5bf..2d19e0ab6 100644
--- a/cde/programs/dtmail/include/MotifApp/Application.h
+++ b/cde/programs/dtmail/include/MotifApp/Application.h
@@ -77,6 +77,7 @@
 #include "UIComponent.h"
 #include <sys/types.h>
 #include <unistd.h>
+#include "MainWindow.h"
 
 class Application : public UIComponent {