diff --git a/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp b/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp
index 3cb65951dd..087ec79109 100644
--- a/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp
+++ b/src/calibre/gui2/progress_indicator/QProgressIndicator.cpp
@@ -8,6 +8,7 @@
 #include <QtWidgets/QProxyStyle>
 #include <QStyleOptionToolButton>
 #include <QFormLayout>
+#include <QDialogButtonBox>
 
 QProgressIndicator::QProgressIndicator(QWidget* parent, int size)
         : QWidget(parent),