diff --git a/src/Mod/Sketcher/App/Sketch.cpp b/src/Mod/Sketcher/App/Sketch.cpp
index 1b1b82ecd7..865c92eaa5 100644
--- a/src/Mod/Sketcher/App/Sketch.cpp
+++ b/src/Mod/Sketcher/App/Sketch.cpp
@@ -1390,6 +1390,19 @@ int Sketch::addConstraint(const Constraint *constraint)
         rtn = addRadiusConstraint(constraint->First, c.value,c.driving);
         break;
     }
+    case Diameter:
+    {
+        c.value = new double(constraint->getValue());
+        if(c.driving)
+            FixParameters.push_back(c.value);
+        else {
+            Parameters.push_back(c.value);
+            DrivenParameters.push_back(c.value);
+        }
+        
+        rtn = addDiameterConstraint(constraint->First, c.value,c.driving);
+        break;
+    }
     case Equal:
         rtn = addEqualConstraint(constraint->First,constraint->Second);
         break;
@@ -2120,6 +2133,25 @@ int Sketch::addRadiusConstraint(int geoId, double * value, bool driving)
     return -1;
 }
 
+int Sketch::addDiameterConstraint(int geoId, double * value, bool driving)
+{
+    geoId = checkGeoId(geoId);
+    
+    if (Geoms[geoId].type == Circle) {
+        GCS::Circle &c = Circles[Geoms[geoId].index];
+        int tag = ++ConstraintsCounter;
+        GCSsys.addConstraintCircleDiameter(c, value, tag, driving);
+        return ConstraintsCounter;
+    }
+    else if (Geoms[geoId].type == Arc) {
+        GCS::Arc &a = Arcs[Geoms[geoId].index];
+        int tag = ++ConstraintsCounter;
+        GCSsys.addConstraintArcDiameter(a, value, tag, driving);
+        return ConstraintsCounter;
+    }
+    return -1;
+}
+
 // line orientation angle constraint
 int Sketch::addAngleConstraint(int geoId, double * value, bool driving)
 {
@@ -3039,6 +3071,10 @@ bool Sketch::updateNonDrivingConstraints()
                 
                 (*it).constr->setValue(std::remainder(*((*it).value), 2.0*M_PI));
             }
+            else if((*it).constr->Type==Diameter) {
+                
+                (*it).constr->setValue(2.0**((*it).value));
+            }
             else {
                 (*it).constr->setValue(*((*it).value));
             }
diff --git a/src/Mod/Sketcher/App/Sketch.h b/src/Mod/Sketcher/App/Sketch.h
index 6aa16056ff..e7e41f2aad 100644
--- a/src/Mod/Sketcher/App/Sketch.h
+++ b/src/Mod/Sketcher/App/Sketch.h
@@ -261,6 +261,14 @@ public:
     *   Parameters array, as the case may be.
     */    
     int addRadiusConstraint(int geoId, double *  value, bool driving = true);
+    /** 
+     *   add a radius constraint on a circle or an arc
+     * 
+     *   double * value is a pointer to double allocated in the heap, containing the
+     *   constraint value and already inserted into either the FixParameters or 
+     *   Parameters array, as the case may be.
+     */    
+    int addDiameterConstraint(int geoId, double *  value, bool driving = true);
     /** 
     *   add an angle constraint on a line or between two lines
     *