diff --git a/src/blackmisc/pqphysicalquantity.cpp b/src/blackmisc/pqphysicalquantity.cpp
index 92e86d177..0e3f951d1 100644
--- a/src/blackmisc/pqphysicalquantity.cpp
+++ b/src/blackmisc/pqphysicalquantity.cpp
@@ -36,6 +36,7 @@ namespace BlackMisc
         template <class MU, class PQ> bool CPhysicalQuantity<MU, PQ>::operator ==(const CPhysicalQuantity<MU, PQ> &other) const
         {
             if (this == &other) return true;
+            if (this->isNull() && other.isNull()) return true; // preliminary fix
             double diff = std::abs(this->m_value - other.value(this->m_unit));
             return diff <= this->m_unit.getEpsilon();
         }
diff --git a/tests/blackmisc/testvariantandmap.cpp b/tests/blackmisc/testvariantandmap.cpp
index 315d6ac7e..5dc52693e 100644
--- a/tests/blackmisc/testvariantandmap.cpp
+++ b/tests/blackmisc/testvariantandmap.cpp
@@ -6,6 +6,7 @@
 #include "testvariantandmap.h"
 #include "blackmisc/avatcstation.h"
 #include "blackmisc/valuemap.h"
+#include "blackmisc/tuple.h"
 #include <QList>
 #include <QString>
 #include <vector>
@@ -39,8 +40,16 @@ namespace BlackMiscTest
                              geoPos, CLength(100, CLengthUnit::km()), false, dtFrom2, dtUntil2);
 
         // compare
+        CLength l1(0, CLengthUnit::nullUnit());
+        CLength l2(0, CLengthUnit::nullUnit());
+        QVERIFY2(l1 == l2, "Null lengths should be equal");
+
         QVariant station1qv = QVariant::fromValue(station1);
         QVERIFY2(station1 == station1, "Station should be equal");
+
+        QVERIFY(station1.getController() == station2.getController());
+        QVERIFY(station1.getDistanceToPlane() == station2.getDistanceToPlane());
+
         QVERIFY2(station1 == station2, "Station should be equal");
         QVERIFY2(station1 != station3, "Station should not be equal");
         QVERIFY2(station1qv == station1, "Station should be equal (QVariant)");