diff --git a/src/prefs/SpectrumPrefs.h b/src/prefs/SpectrumPrefs.h
index 9a3ad1370..61cc0f89b 100644
--- a/src/prefs/SpectrumPrefs.h
+++ b/src/prefs/SpectrumPrefs.h
@@ -74,8 +74,9 @@ class SpectrumPrefs:public PrefsPanel
 };
 
 
-struct SpectrogramSettings
+class SpectrogramSettings
 {
+public:
    static SpectrogramSettings &defaults();
    SpectrogramSettings();
    ~SpectrogramSettings();