diff --git a/src/blackmisc/aviation/modulator.cpp b/src/blackmisc/aviation/modulator.cpp
index c2ed11c6b..605ca1842 100644
--- a/src/blackmisc/aviation/modulator.cpp
+++ b/src/blackmisc/aviation/modulator.cpp
@@ -165,6 +165,9 @@ namespace BlackMisc
         CModulator<AVIO>::CModulator(const QString &name, const BlackMisc::PhysicalQuantities::CFrequency &activeFrequency, const BlackMisc::PhysicalQuantities::CFrequency &standbyFrequency) :
             m_name(name), m_frequencyActive(activeFrequency), m_frequencyStandby(standbyFrequency) {}
 
+        template <class AVIO>
+        CModulator<AVIO>::~CModulator() {}
+
         template <class AVIO>
         QString CModulator<AVIO>::convertToQString(bool i18n) const
         {
diff --git a/src/blackmisc/aviation/modulator.h b/src/blackmisc/aviation/modulator.h
index 7bab06479..d0f805475 100644
--- a/src/blackmisc/aviation/modulator.h
+++ b/src/blackmisc/aviation/modulator.h
@@ -95,6 +95,9 @@ namespace BlackMisc
             //! Constructor
             CModulator(const QString &name, const BlackMisc::PhysicalQuantities::CFrequency &activeFrequency, const BlackMisc::PhysicalQuantities::CFrequency &standbyFrequency);
 
+            //! Destructor
+            virtual ~CModulator();
+
             //! Set active frequency
             void setFrequencyActiveKHz(double frequencyKHz);
 
diff --git a/src/blackmisc/aviation/transponder.h b/src/blackmisc/aviation/transponder.h
index d034e4a3d..68f7d21bf 100644
--- a/src/blackmisc/aviation/transponder.h
+++ b/src/blackmisc/aviation/transponder.h
@@ -166,11 +166,10 @@ namespace BlackMisc
             //! \copydoc CValueObject::convertToQString
             QString convertToQString(bool i18n = false) const;
 
-        protected:
-            //! Default value?
-            virtual bool isDefaultValue() const { return this->m_transponderCode == 0; }
-
         private:
+            //! Default value?
+            bool isDefaultValue() const { return this->m_transponderCode == 0; }
+
             BLACK_ENABLE_TUPLE_CONVERSION(CTransponder)
             int m_transponderCode;             //!< Transponder code
             TransponderMode m_transponderMode; //!< Transponder mode