diff --git a/src/Base/Quantity.cpp b/src/Base/Quantity.cpp
index f5dbb3a453..446e0dd555 100644
--- a/src/Base/Quantity.cpp
+++ b/src/Base/Quantity.cpp
@@ -83,10 +83,23 @@ Quantity::Quantity(const Quantity& that)
     *this = that ;
 }
 
-Quantity::Quantity(double Value, const Unit& unit)
+Quantity::Quantity(double value, const Unit& unit)
 {
     this->_Unit = unit;
-    this->_Value = Value;
+    this->_Value = value;
+}
+
+Quantity::Quantity(double value, const QString& unit)
+{
+    try {
+        auto tmpQty = parse(unit);
+        this->_Unit = tmpQty.getUnit();
+        this->_Value = value * tmpQty.getValue();
+    }
+    catch (const Base::Exception&) {
+        this->_Value = 0.0;
+        this->_Unit = Unit();
+    }
 }
 
 double Quantity::getValueAs(const Quantity &q)const
diff --git a/src/Base/Quantity.h b/src/Base/Quantity.h
index 1aee268d6a..cb8c3dbfdd 100644
--- a/src/Base/Quantity.h
+++ b/src/Base/Quantity.h
@@ -113,7 +113,8 @@ public:
     /// default constructor
     Quantity(void);
     Quantity(const Quantity&);
-    explicit Quantity(double Value, const Unit& unit=Unit());
+    explicit Quantity(double value, const Unit& unit=Unit());
+    explicit Quantity(double value, const QString& unit);
     /// Destruction
     ~Quantity () {}
 
diff --git a/src/Base/Unit.h b/src/Base/Unit.h
index 048b8b3f01..665813ef80 100644
--- a/src/Base/Unit.h
+++ b/src/Base/Unit.h
@@ -66,7 +66,7 @@ public:
     Unit(int8_t Length,int8_t Mass=0,int8_t Time=0,int8_t ElectricCurrent=0,int8_t ThermodynamicTemperature=0,int8_t AmountOfSubstance=0,int8_t LuminousIntensity=0,int8_t Angle=0);
     Unit(void);
     Unit(const Unit&);
-    Unit(const QString& expr);
+    explicit Unit(const QString& expr);
     /// Destruction
     ~Unit () {}