diff --git a/src/Gui/Thumbnail.cpp b/src/Gui/Thumbnail.cpp
index 354c0e357..df5cbdf3a 100644
--- a/src/Gui/Thumbnail.cpp
+++ b/src/Gui/Thumbnail.cpp
@@ -24,6 +24,7 @@
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
+# include <QApplication>
 # include <QBuffer>
 # include <QByteArray>
 # include <QDateTime>