diff --git a/src/blackmisc/comparefunctions.cpp b/src/blackmisc/comparefunctions.cpp
index 1a9f4718f..ecae024f8 100644
--- a/src/blackmisc/comparefunctions.cpp
+++ b/src/blackmisc/comparefunctions.cpp
@@ -40,7 +40,7 @@ namespace BlackMisc
 
         int compare(double a, double b)
         {
-            if (a == b) return 0;
+            if (qFuzzyCompare(a, b)) return 0;
             return a < b ? -1 : 1;
         }
 
diff --git a/src/blackmisc/pq/measurementunit.cpp b/src/blackmisc/pq/measurementunit.cpp
index cc6102417..aa671baef 100644
--- a/src/blackmisc/pq/measurementunit.cpp
+++ b/src/blackmisc/pq/measurementunit.cpp
@@ -48,7 +48,7 @@ namespace BlackMisc
 
         double CMeasurementUnit::roundToEpsilon(double value) const
         {
-            if (this->getEpsilon() == 0 || this->isNull()) { return value; }
+            if (qFuzzyIsNull(getEpsilon()) || this->isNull()) { return value; }
             return CMathUtils::roundEpsilon(value, this->getEpsilon());
         }
 
diff --git a/src/blackmisc/pq/measurementunit.h b/src/blackmisc/pq/measurementunit.h
index ba6f9cfbc..a54885819 100644
--- a/src/blackmisc/pq/measurementunit.h
+++ b/src/blackmisc/pq/measurementunit.h
@@ -333,7 +333,7 @@ namespace BlackMisc
             bool isEpsilon(double value) const
             {
                 if (this->isNull()) return false;
-                if (value == 0) return true;
+                if (qFuzzyIsNull(value)) return true;
                 return std::abs(value) <= this->m_data->m_epsilon;
             }
 
diff --git a/src/blackmisc/pq/physicalquantity.cpp b/src/blackmisc/pq/physicalquantity.cpp
index 8737a92e0..0d9ac6326 100644
--- a/src/blackmisc/pq/physicalquantity.cpp
+++ b/src/blackmisc/pq/physicalquantity.cpp
@@ -145,7 +145,7 @@ namespace BlackMisc
         template <class MU, class PQ>
         const PQ &CPhysicalQuantity<MU, PQ>::makePositive()
         {
-            if (this->isNull() || m_value == 0) { return *this->derived(); }
+            if (this->isNull() || qFuzzyIsNull(m_value)) { return *this->derived(); }
             if (m_value < 0) { m_value *= -1.0; }
             return *this->derived();
         }
@@ -153,7 +153,7 @@ namespace BlackMisc
         template <class MU, class PQ>
         const PQ &CPhysicalQuantity<MU, PQ>::makeNegative()
         {
-            if (this->isNull() || m_value == 0) { return *this->derived(); }
+            if (this->isNull() || qFuzzyIsNull(m_value)) { return *this->derived(); }
             if (m_value > 0) { m_value *= -1.0; }
             return *this->derived();
         }
@@ -161,7 +161,7 @@ namespace BlackMisc
         template<class MU, class PQ>
         PQ CPhysicalQuantity<MU, PQ>::abs() const
         {
-            if (this->isNull() || m_value == 0) { return *this->derived(); }
+            if (this->isNull() || qFuzzyIsNull(m_value)) { return *this->derived(); }
             if (m_value >= 0) { return *this->derived(); }
             PQ copy(*this->derived());
             return copy.makePositive();