diff --git a/xs/src/ClipperUtils.cpp b/xs/src/ClipperUtils.cpp
index 2989783ee..12c90996f 100644
--- a/xs/src/ClipperUtils.cpp
+++ b/xs/src/ClipperUtils.cpp
@@ -1,6 +1,14 @@
 #include "ClipperUtils.hpp"
 #include "Geometry.hpp"
 
+#ifndef use_lines
+    #error "use_lines directive is not enabled in clipper.hpp"
+#endif
+
+#ifdef use_deprecated
+    #error "use_deprecated is not disabled in clipper.hpp"
+#endif
+
 namespace Slic3r {
 
 //-----------------------------------------------------------
diff --git a/xs/src/clipper.cpp b/xs/src/clipper.cpp
index 936e2524d..9070ecb1b 100644
--- a/xs/src/clipper.cpp
+++ b/xs/src/clipper.cpp
@@ -2,7 +2,7 @@
 *                                                                              *
 * Author    :  Angus Johnson                                                   *
 * Version   :  6.1.5                                                           *
-* Date      :  22 May 2014                                                     *
+* Date      :  24 May 2014                                                     *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2014                                         *
 *                                                                              *
@@ -898,112 +898,39 @@ TEdge* FindNextLocMin(TEdge* E)
 }
 //------------------------------------------------------------------------------
 
-TEdge* ClipperBase::ProcessBound(TEdge* E, bool IsClockwise)
+TEdge* ClipperBase::ProcessBound(TEdge* E, bool NextIsForward)
 {
   TEdge *EStart = E, *Result = E;
   TEdge *Horz = 0;
   cInt StartX;
-  if (IsHorizontal(*E))
-  {
-	//first we need to be careful here with open paths because this
-	//may not be a true local minima (ie may be following a skip edge).
-	//also, watch for adjacent horz edges to start heading left
-	//before finishing right ...
-	if (IsClockwise)
-	{
-		if (E->Prev->Bot.Y == E->Bot.Y) StartX = E->Prev->Bot.X;
-		else StartX = E->Prev->Top.X;
-	}
-	else
-	{
-		if (E->Next->Bot.Y == E->Bot.Y) StartX = E->Next->Bot.X;
-		else StartX = E->Next->Top.X;
-	}
-    if (E->Bot.X != StartX) ReverseHorizontal(*E);
-  }
-  
-  if (Result->OutIdx != Skip)
-  {
-    if (IsClockwise)
-    {
-      while (Result->Top.Y == Result->Next->Bot.Y && Result->Next->OutIdx != Skip)
-        Result = Result->Next;
-      if (IsHorizontal(*Result) && Result->Next->OutIdx != Skip)
-      {
-        //nb: at the top of a bound, horizontals are added to the bound
-        //only when the preceding edge attaches to the horizontal's left vertex
-        //unless a Skip edge is encountered when that becomes the top divide
-        Horz = Result;
-        while (IsHorizontal(*Horz->Prev)) Horz = Horz->Prev;
-        if (Horz->Prev->Top.X == Result->Next->Top.X) 
-        {
-          if (!IsClockwise) Result = Horz->Prev;
-        }
-        else if (Horz->Prev->Top.X > Result->Next->Top.X) Result = Horz->Prev;
-      }
-      while (E != Result) 
-      {
-        E->NextInLML = E->Next;
-        if (IsHorizontal(*E) && E != EStart &&
-          E->Bot.X != E->Prev->Top.X) ReverseHorizontal(*E);
-        E = E->Next;
-      }
-      if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Prev->Top.X) 
-        ReverseHorizontal(*E);
-      Result = Result->Next; //move to the edge just beyond current bound
-    } else
-    {
-      while (Result->Top.Y == Result->Prev->Bot.Y && Result->Prev->OutIdx != Skip) 
-        Result = Result->Prev;
-      if (IsHorizontal(*Result) && Result->Prev->OutIdx != Skip)
-      {
-        Horz = Result;
-        while (IsHorizontal(*Horz->Next)) Horz = Horz->Next;
-        if (Horz->Next->Top.X == Result->Prev->Top.X) 
-        {
-          if (!IsClockwise) Result = Horz->Next;
-        }
-        else if (Horz->Next->Top.X > Result->Prev->Top.X) Result = Horz->Next;
-      }
 
-      while (E != Result)
-      {
-        E->NextInLML = E->Prev;
-        if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X) 
-          ReverseHorizontal(*E);
-        E = E->Prev;
-      }
-      if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X) 
-        ReverseHorizontal(*E);
-      Result = Result->Prev; //move to the edge just beyond current bound
-    }
-  }
-
-  if (Result->OutIdx == Skip) 
+  if (E->OutIdx == Skip)
   {
     //if edges still remain in the current bound beyond the skip edge then
     //create another LocMin and call ProcessBound once more
-    E = Result;
-    if (IsClockwise)
+    if (NextIsForward)
     {
       while (E->Top.Y == E->Next->Bot.Y) E = E->Next;
       //don't include top horizontals when parsing a bound a second time,
       //they will be contained in the opposite bound ...
       while (E != Result && IsHorizontal(*E)) E = E->Prev;
-    } else
+    }
+    else
     {
       while (E->Top.Y == E->Prev->Bot.Y) E = E->Prev;
       while (E != Result && IsHorizontal(*E)) E = E->Next;
     }
+
     if (E == Result)
     {
-      if (IsClockwise) Result = E->Next;
+      if (NextIsForward) Result = E->Next;
       else Result = E->Prev;
-    } else
+    }
+    else
     {
       //there are more edges in the bound beyond result starting with E
-      if (IsClockwise)
-        E = Result->Next; 
+      if (NextIsForward)
+        E = Result->Next;
       else
         E = Result->Prev;
       LocalMinima* locMin = new LocalMinima;
@@ -1012,10 +939,85 @@ TEdge* ClipperBase::ProcessBound(TEdge* E, bool IsClockwise)
       locMin->LeftBound = 0;
       locMin->RightBound = E;
       locMin->RightBound->WindDelta = 0;
-      Result = ProcessBound(locMin->RightBound, IsClockwise);
+      Result = ProcessBound(locMin->RightBound, NextIsForward);
       InsertLocalMinima(locMin);
     }
+    return Result;
   }
+
+  if (IsHorizontal(*E))
+  {
+	  //we need to be careful with open paths because this may not be 
+    //a true local minima (ie may be following a skip edge).
+	  //Also, watch for adjacent horz edges that can head left
+	  //before finishing right ...
+	  if (NextIsForward)
+	  {
+		  if (E->Prev->Bot.Y == E->Bot.Y) StartX = E->Prev->Bot.X;
+		  else StartX = E->Prev->Top.X;
+	  }
+	  else
+	  {
+		  if (E->Next->Bot.Y == E->Bot.Y) StartX = E->Next->Bot.X;
+		  else StartX = E->Next->Top.X;
+	  }
+    if (E->Bot.X != StartX) ReverseHorizontal(*E);
+  }
+  
+  if (NextIsForward)
+  {
+    while (Result->Top.Y == Result->Next->Bot.Y && Result->Next->OutIdx != Skip)
+      Result = Result->Next;
+    if (IsHorizontal(*Result) && Result->Next->OutIdx != Skip)
+    {
+      //nb: at the top of a bound, horizontals are added to the bound
+      //only when the preceding edge attaches to the horizontal's left vertex
+      //unless a Skip edge is encountered when that becomes the top divide
+      Horz = Result;
+      while (IsHorizontal(*Horz->Prev)) Horz = Horz->Prev;
+      if (Horz->Prev->Top.X == Result->Next->Top.X) 
+      {
+        if (!NextIsForward) Result = Horz->Prev;
+      }
+      else if (Horz->Prev->Top.X > Result->Next->Top.X) Result = Horz->Prev;
+    }
+    while (E != Result) 
+    {
+      E->NextInLML = E->Next;
+      if (IsHorizontal(*E) && E != EStart &&
+        E->Bot.X != E->Prev->Top.X) ReverseHorizontal(*E);
+      E = E->Next;
+    }
+    if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Prev->Top.X) 
+      ReverseHorizontal(*E);
+    Result = Result->Next; //move to the edge just beyond current bound
+  } else
+  {
+    while (Result->Top.Y == Result->Prev->Bot.Y && Result->Prev->OutIdx != Skip) 
+      Result = Result->Prev;
+    if (IsHorizontal(*Result) && Result->Prev->OutIdx != Skip)
+    {
+      Horz = Result;
+      while (IsHorizontal(*Horz->Next)) Horz = Horz->Next;
+      if (Horz->Next->Top.X == Result->Prev->Top.X) 
+      {
+        if (!NextIsForward) Result = Horz->Next;
+      }
+      else if (Horz->Next->Top.X > Result->Prev->Top.X) Result = Horz->Next;
+    }
+
+    while (E != Result)
+    {
+      E->NextInLML = E->Prev;
+      if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X) 
+        ReverseHorizontal(*E);
+      E = E->Prev;
+    }
+    if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X) 
+      ReverseHorizontal(*E);
+    Result = Result->Prev; //move to the edge just beyond current bound
+  }
+
   return Result;
 }
 //------------------------------------------------------------------------------
@@ -1148,7 +1150,7 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
   }
 
   m_edges.push_back(edges);
-  bool clockwise;
+  bool nextIsForward;
   TEdge* EMin = 0;
 
   //workaround to avoid an endless loop in the while loop below when
@@ -1170,12 +1172,12 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
     {
       locMin->LeftBound = E->Prev;
       locMin->RightBound = E;
-      clockwise = false; //Q.nextInLML = Q.prev
+      nextIsForward = false; //Q.nextInLML = Q.prev
     } else
     {
       locMin->LeftBound = E;
       locMin->RightBound = E->Prev;
-      clockwise = true; //Q.nextInLML = Q.next
+      nextIsForward = true; //Q.nextInLML = Q.next
     }
     locMin->LeftBound->Side = esLeft;
     locMin->RightBound->Side = esRight;
@@ -1186,15 +1188,15 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
     else locMin->LeftBound->WindDelta = 1;
     locMin->RightBound->WindDelta = -locMin->LeftBound->WindDelta;
 
-    E = ProcessBound(locMin->LeftBound, clockwise);
-    TEdge* E2 = ProcessBound(locMin->RightBound, !clockwise);
+    E = ProcessBound(locMin->LeftBound, nextIsForward);
+    TEdge* E2 = ProcessBound(locMin->RightBound, !nextIsForward);
 
     if (locMin->LeftBound->OutIdx == Skip)
       locMin->LeftBound = 0;
     else if (locMin->RightBound->OutIdx == Skip)
       locMin->RightBound = 0;
     InsertLocalMinima(locMin);
-    if (!clockwise) E = E2;
+    if (!nextIsForward) E = E2;
   }
   return true;
 }
diff --git a/xs/src/clipper.hpp b/xs/src/clipper.hpp
index 7922abe18..9927a97ad 100644
--- a/xs/src/clipper.hpp
+++ b/xs/src/clipper.hpp
@@ -2,7 +2,7 @@
 *                                                                              *
 * Author    :  Angus Johnson                                                   *
 * Version   :  6.1.5                                                           *
-* Date      :  22 May 2014                                                     *
+* Date      :  24 May 2014                                                     *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2014                                         *
 *                                                                              *
diff --git a/xs/t/11_clipper.t b/xs/t/11_clipper.t
index efa051fe7..89d173e39 100644
--- a/xs/t/11_clipper.t
+++ b/xs/t/11_clipper.t
@@ -155,7 +155,7 @@ if (0) {  # Clipper does not preserve polyline orientation
     }
 }
 
-# Disabled until Clipper bug #96 (our issue #2028) is fixed
+# Clipper bug #96 (our GH #2028)
 if (0) {
     my $subject = Slic3r::Polyline->new(
         [44735000,31936670],[55270000,31936670],[55270000,25270000],[74730000,25270000],[74730000,44730000],[68063296,44730000],[68063296,55270000],[74730000,55270000],[74730000,74730000],[55270000,74730000],[55270000,68063296],[44730000,68063296],[44730000,74730000],[25270000,74730000],[25270000,55270000],[31936670,55270000],[31936670,44730000],[25270000,44730000],[25270000,25270000],[44730000,25270000],[44730000,31936670]