diff -r 1381ce67a781 -r 7f8f2c77a9cc QTfrontend/ui/widget/mapContainer.cpp
--- a/QTfrontend/ui/widget/mapContainer.cpp	Mon Mar 19 15:21:11 2018 +0100
+++ b/QTfrontend/ui/widget/mapContainer.cpp	Mon Mar 19 15:44:39 2018 +0100
@@ -1247,7 +1247,8 @@
     iconMissing.addPixmap(pixMissing, QIcon::Normal);
     iconMissing.addPixmap(pixMissing, QIcon::Disabled);
     btnTheme->setIcon(iconMissing);
-    btnTheme->setText(tr("Theme: %1").arg(name));
+    // Question mark in front of theme name denotes it's missing
+    btnTheme->setText(tr("Theme: %1").arg("?" + name));
     updateThemeButtonSize();
 }