diff --git a/src/blackmisc/avaircraft.h b/src/blackmisc/avaircraft.h
index 3acc16286..5efff5122 100644
--- a/src/blackmisc/avaircraft.h
+++ b/src/blackmisc/avaircraft.h
@@ -28,11 +28,11 @@ namespace BlackMisc
         {
         public:
             //! \brief Default constructor.
-            CAircraft() : m_distanceToPlane(-1.0, BlackMisc::PhysicalQuantities::CLengthUnit::NM()) {}
+            CAircraft() : m_distanceToPlane(0, BlackMisc::PhysicalQuantities::CLengthUnit::nullUnit()) {}
 
             //! \brief Constructor.
             CAircraft(const CCallsign &callsign, const BlackMisc::Network::CUser &user, const CAircraftSituation &situation)
-                : m_callsign(callsign), m_pilot(user), m_situation(situation), m_distanceToPlane(-1.0, BlackMisc::PhysicalQuantities::CLengthUnit::NM()) {}
+                : m_callsign(callsign), m_pilot(user), m_situation(situation), m_distanceToPlane(0, BlackMisc::PhysicalQuantities::CLengthUnit::nullUnit()) {}
 
             //! \copydoc CValueObject::toQVariant
             virtual QVariant toQVariant() const override
diff --git a/src/blackmisc/avatcstation.cpp b/src/blackmisc/avatcstation.cpp
index 66de8b70b..f20254b70 100644
--- a/src/blackmisc/avatcstation.cpp
+++ b/src/blackmisc/avatcstation.cpp
@@ -17,7 +17,7 @@ namespace BlackMisc
          * Constructor
          */
         CAtcStation::CAtcStation()  :
-            m_distanceToPlane(-1.0, CLengthUnit::NM()), m_isOnline(false), m_atis(CInformationMessage::ATIS), m_metar(CInformationMessage::METAR)
+            m_distanceToPlane(0, CLengthUnit::nullUnit()), m_isOnline(false), m_atis(CInformationMessage::ATIS), m_metar(CInformationMessage::METAR)
         {
             // void
         }
@@ -26,7 +26,7 @@ namespace BlackMisc
          * Constructor
          */
         CAtcStation::CAtcStation(const QString &callsign)  :
-            m_callsign(callsign), m_distanceToPlane(-1.0, CLengthUnit::NM()), m_isOnline(false), m_atis(CInformationMessage::ATIS), m_metar(CInformationMessage::METAR)
+            m_callsign(callsign), m_distanceToPlane(0, CLengthUnit::nullUnit()), m_isOnline(false), m_atis(CInformationMessage::ATIS), m_metar(CInformationMessage::METAR)
         {
             // void
         }
@@ -37,7 +37,7 @@ namespace BlackMisc
         CAtcStation::CAtcStation(const CCallsign &callsign, const CUser &controller, const CFrequency &frequency, const CCoordinateGeodetic &pos, const CLength &range, bool isOnline,
                                  const QDateTime &bookedFromUtc, const QDateTime &bookedUntilUtc, const CInformationMessage &atis, const CInformationMessage &metar) :
             m_callsign(callsign), m_controller(controller), m_frequency(frequency), m_position(pos),
-            m_range(range), m_distanceToPlane(-1.0, CLengthUnit::NM()), m_isOnline(isOnline),
+            m_range(range), m_distanceToPlane(0, CLengthUnit::nullUnit()), m_isOnline(isOnline),
             m_bookedFromUtc(bookedFromUtc), m_bookedUntilUtc(bookedUntilUtc), m_atis(atis), m_metar(metar)
         {
             // void
diff --git a/src/blackmisc/nwtextmessage.h b/src/blackmisc/nwtextmessage.h
index 987a5a367..2cae888a8 100644
--- a/src/blackmisc/nwtextmessage.h
+++ b/src/blackmisc/nwtextmessage.h
@@ -28,7 +28,7 @@ namespace BlackMisc
             /*!
              * Default constructor.
              */
-            CTextMessage() : m_received(QDateTime::currentDateTimeUtc()), m_frequency(-1.0, BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz()) {}
+            CTextMessage() : m_received(QDateTime::currentDateTimeUtc()), m_frequency(0, BlackMisc::PhysicalQuantities::CFrequencyUnit::nullUnit()) {}
 
             /*!
              * Constructor, radio message
@@ -43,7 +43,7 @@ namespace BlackMisc
              * Constructor, private message
              */
             CTextMessage(const QString &message, const BlackMisc::Aviation::CCallsign &senderCallsign, const BlackMisc::Aviation::CCallsign &recipientCallsign = BlackMisc::Aviation::CCallsign())
-                : m_message(message), m_received(QDateTime::currentDateTimeUtc()), m_senderCallsign(senderCallsign), m_recipientCallsign(recipientCallsign), m_frequency(-1.0, BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz()) {}
+                : m_message(message), m_received(QDateTime::currentDateTimeUtc()), m_senderCallsign(senderCallsign), m_recipientCallsign(recipientCallsign), m_frequency(0, BlackMisc::PhysicalQuantities::CFrequencyUnit::nullUnit()) {}
 
             /*!
              * Get callsign (from)