diff --git a/src/plugins/platformthemes/gtk3/qgtk3theme.cpp b/src/plugins/platformthemes/gtk3/qgtk3theme.cpp
index b00d618f7e2..09087cf4ef3 100644
--- a/src/plugins/platformthemes/gtk3/qgtk3theme.cpp
+++ b/src/plugins/platformthemes/gtk3/qgtk3theme.cpp
@@ -190,7 +190,7 @@ QPlatformTheme::Appearance QGtk3Theme::appearance() const
         gtk-theme-name provides both light and dark variants. We can save a
         regex check by testing this property first.
     */
-    const auto preferDark = gtkSetting<bool>("gtk-application-prefer-dark-theme");
+    const auto preferDark = gtkSetting<gboolean>("gtk-application-prefer-dark-theme");
     if (preferDark)
         return Appearance::Dark;