diff --git a/src/Mod/PartDesign/App/FeatureFace.cpp b/src/Mod/PartDesign/App/FeatureFace.cpp
index 55030f6c9..fb4b81dcf 100644
--- a/src/Mod/PartDesign/App/FeatureFace.cpp
+++ b/src/Mod/PartDesign/App/FeatureFace.cpp
@@ -105,23 +105,25 @@ App::DocumentObjectExecReturn *Face::execute(void)
     return App::DocumentObject::StdReturn;
 }
 
-namespace PartDesign {
-
 // sort bounding boxes according to diagonal length
-struct Wire_Compare {
+class Face::Wire_Compare {
+public:
     bool operator() (const TopoDS_Wire& w1, const TopoDS_Wire& w2)
     {
         Bnd_Box box1, box2;
-        BRepBndLib::Add(w1, box1);
-        box1.SetGap(0.0);
+        if (!w1.IsNull()) {
+            BRepBndLib::Add(w1, box1);
+            box1.SetGap(0.0);
+        }
 
-        BRepBndLib::Add(w2, box2);
-        box2.SetGap(0.0);
+        if (!w2.IsNull()) {
+            BRepBndLib::Add(w2, box2);
+            box2.SetGap(0.0);
+        }
 
         return box1.SquareExtent() < box2.SquareExtent();
     }
 };
-}
 
 TopoDS_Shape Face::makeFace(std::list<TopoDS_Wire>& wires) const
 {
diff --git a/src/Mod/PartDesign/App/FeatureFace.h b/src/Mod/PartDesign/App/FeatureFace.h
index b30ec92ef..2cb69bd91 100644
--- a/src/Mod/PartDesign/App/FeatureFace.h
+++ b/src/Mod/PartDesign/App/FeatureFace.h
@@ -48,6 +48,9 @@ public:
 protected:
     TopoDS_Shape makeFace(const std::vector<TopoDS_Wire>&) const;
     TopoDS_Shape makeFace(std::list<TopoDS_Wire>&) const; // for internal use only
+
+private:
+    class Wire_Compare;
 };
 
 } //namespace PartDesign
diff --git a/src/Mod/PartDesign/App/FeatureSketchBased.cpp b/src/Mod/PartDesign/App/FeatureSketchBased.cpp
index c5c856761..0e2027160 100644
--- a/src/Mod/PartDesign/App/FeatureSketchBased.cpp
+++ b/src/Mod/PartDesign/App/FeatureSketchBased.cpp
@@ -69,18 +69,21 @@
 
 using namespace PartDesign;
 
-namespace PartDesign {
-
 // sort bounding boxes according to diagonal length
-struct Wire_Compare {
+class SketchBased::Wire_Compare {
+public:
     bool operator() (const TopoDS_Wire& w1, const TopoDS_Wire& w2)
     {
         Bnd_Box box1, box2;
-        BRepBndLib::Add(w1, box1);
-        box1.SetGap(0.0);
+        if (!w1.IsNull()) {
+            BRepBndLib::Add(w1, box1);
+            box1.SetGap(0.0);
+        }
 
-        BRepBndLib::Add(w2, box2);
-        box2.SetGap(0.0);
+        if (!w2.IsNull()) {
+            BRepBndLib::Add(w2, box2);
+            box2.SetGap(0.0);
+        }
 
         return box1.SquareExtent() < box2.SquareExtent();
     }
@@ -799,6 +802,7 @@ void SketchBased::remapSupportShape(const TopoDS_Shape& newShape)
     }
 }
 
+namespace PartDesign {
 struct gp_Pnt_Less  : public std::binary_function<const gp_Pnt&,
                                                   const gp_Pnt&, bool>
 {
@@ -814,6 +818,7 @@ struct gp_Pnt_Less  : public std::binary_function<const gp_Pnt&,
         return false; // points are considered to be equal
     }
 };
+}
 
 bool SketchBased::isQuasiEqual(const TopoDS_Shape& s1, const TopoDS_Shape& s2) const
 {
@@ -895,5 +900,3 @@ bool SketchBased::isParallelPlane(const TopoDS_Shape& s1, const TopoDS_Shape& s2
 
     return false;
 }
-
-}
diff --git a/src/Mod/PartDesign/App/FeatureSketchBased.h b/src/Mod/PartDesign/App/FeatureSketchBased.h
index ad45c76f0..863c382a7 100644
--- a/src/Mod/PartDesign/App/FeatureSketchBased.h
+++ b/src/Mod/PartDesign/App/FeatureSketchBased.h
@@ -119,6 +119,8 @@ protected:
     /// Check whether the line crosses the face (line and face must be on the same plane)
     static const bool checkLineCrossesFace(const gp_Lin& line, const TopoDS_Face& face);
 
+private:
+    class Wire_Compare;
 };
 
 } //namespace PartDesign