diff --git a/src/gui/FileDialog.cpp b/src/gui/FileDialog.cpp
index 7dd02b17d..844825850 100644
--- a/src/gui/FileDialog.cpp
+++ b/src/gui/FileDialog.cpp
@@ -67,6 +67,7 @@ QString FileDialog::getSaveFileName(QWidget* parent, const QString& caption, QSt
 
         QString result;
 #if defined(Q_OS_MAC) || defined(Q_OS_WIN)
+        Q_UNUSED(defaultExtension);
         // the native dialogs on these platforms already append the file extension
         result = QFileDialog::getSaveFileName(parent, caption, dir, filter,
                                               selectedFilter, options);