diff --git a/src/db/db/dbEdgePairRelations.cc b/src/db/db/dbEdgePairRelations.cc
index 64d23cc43..345e04066 100644
--- a/src/db/db/dbEdgePairRelations.cc
+++ b/src/db/db/dbEdgePairRelations.cc
@@ -113,7 +113,7 @@ bool euclidian_near_part_of_edge (bool include_zero, db::Coord d, const db::Edge
 
   //  handle the parallel case
   if (e.parallel (g)) {
-    if (abs (e.distance (g.p1 ())) >= d) {
+    if (std::abs (e.distance (g.p1 ())) >= d) {
       return false;
     }
   } else {
@@ -243,7 +243,7 @@ static bool var_near_part_of_edge (bool include_zero, db::Coord d, db::Coord dd,
 
   //  handle the parallel case
   if (e.parallel (g)) {
-    if (abs (e.distance (g.p1 ())) >= d) {
+    if (std::abs (e.distance (g.p1 ())) >= d) {
       return false;
     }
   } else {
diff --git a/src/db/db/dbPolygonTools.cc b/src/db/db/dbPolygonTools.cc
index 641184eeb..18d850929 100644
--- a/src/db/db/dbPolygonTools.cc
+++ b/src/db/db/dbPolygonTools.cc
@@ -26,6 +26,7 @@
 #include "dbPolygonTools.h"
 #include "dbPolygonGenerators.h"
 #include "tlLog.h"
+#include "tlInt128Support.h"
 
 #include <algorithm>
 #include <cmath>
@@ -706,7 +707,7 @@ smooth_contour (db::Polygon::polygon_contour_iterator from, db::Polygon::polygon
       }
 
       for (size_t j = pi0; can_drop; ) {
-        if (abs (db::Edge (p0, p2).distance (org_points [j])) > d) {
+        if (std::abs (db::Edge (p0, p2).distance (org_points [j])) > d) {
           can_drop = false;
         }
         if (j == pi2) {
diff --git a/src/db/unit_tests/dbGDS2Writer.cc b/src/db/unit_tests/dbGDS2Writer.cc
index a6cd5cd07..7e714514e 100644
--- a/src/db/unit_tests/dbGDS2Writer.cc
+++ b/src/db/unit_tests/dbGDS2Writer.cc
@@ -176,7 +176,7 @@ TEST(3)
                       layout_read, top_read, j, 
                       top_org.shapes (xor_layer), db::BooleanOp::Xor, true, false); 
           EXPECT_EQ (top_org.shapes (xor_layer).size () > 210, true);
-          sp.size (layout_org, top_org, xor_layer, top_org.shapes (xor_layer), -1, -1);
+          sp.size (layout_org, top_org, xor_layer, top_org.shapes (xor_layer), db::Coord (-1), db::Coord (-1));
           EXPECT_EQ (top_org.shapes (xor_layer).size () == 0, true);
         }
       }
@@ -236,7 +236,7 @@ TEST(4)
           sp.boolean (layout_org, top_org, i, 
                       layout_read, top_read, j, 
                       top_org.shapes (xor_layer), db::BooleanOp::Xor, true, false); 
-          sp.size (layout_org, top_org, xor_layer, top_org.shapes (xor_layer), -1, -1);
+          sp.size (layout_org, top_org, xor_layer, top_org.shapes (xor_layer), db::Coord (-1), db::Coord (-1));
           EXPECT_EQ (top_org.shapes (xor_layer).size () == 0, true);
         }
       }
diff --git a/src/db/unit_tests/dbOASISWriter2.cc b/src/db/unit_tests/dbOASISWriter2.cc
index b3d86c528..ccbdc0e5e 100644
--- a/src/db/unit_tests/dbOASISWriter2.cc
+++ b/src/db/unit_tests/dbOASISWriter2.cc
@@ -81,7 +81,7 @@ TEST(1)
           sp.boolean (layout_org, top_org, i, 
                       layout_read, top_read, j, 
                       top_org.shapes (xor_layer), db::BooleanOp::Xor, true, false); 
-          sp.size (layout_org, top_org, xor_layer, top_org.shapes (xor_layer), -1, -1);
+          sp.size (layout_org, top_org, xor_layer, top_org.shapes (xor_layer), db::Coord (-1), db::Coord (-1));
           EXPECT_EQ (top_org.shapes (xor_layer).size () == 0, true);
         }
       }
diff --git a/src/db/unit_tests/dbPolygon.cc b/src/db/unit_tests/dbPolygon.cc
index 5d087b21d..7248bb7b1 100644
--- a/src/db/unit_tests/dbPolygon.cc
+++ b/src/db/unit_tests/dbPolygon.cc
@@ -1026,19 +1026,19 @@ TEST(20)
   EXPECT_EQ (poly.to_string (), "(100,100;200,100;200,400;100,400;100,300;400,300;400,400;300,400;300,100;400,100;400,200;100,200)");
 
   poly.assign_hull (pts, pts + sizeof (pts) / sizeof (pts[0]));
-  poly.size (100, 0);
+  poly.size (db::Coord (100), db::Coord (0));
   EXPECT_EQ (poly.to_string (), "(0,100;0,400;500,400;500,100)");
 
   poly.assign_hull (pts, pts + sizeof (pts) / sizeof (pts[0]));
-  poly.size (0, 100);
+  poly.size (db::Coord (0), db::Coord (100));
   EXPECT_EQ (poly.to_string (), "(100,0;100,500;400,500;400,0)");
 
   poly.assign_hull (pts, pts + sizeof (pts) / sizeof (pts[0]));
-  poly.size (-100, 0);
+  poly.size (db::Coord (-100), db::Coord (0));
   EXPECT_EQ (poly.to_string (), "(100,100;200,100;200,400;100,400;400,400;300,400;300,100;400,100)");
 
   poly.assign_hull (pts, pts + sizeof (pts) / sizeof (pts[0]));
-  poly.size (0, -100);
+  poly.size (db::Coord (0), db::Coord (-100));
   EXPECT_EQ (poly.to_string (), "(100,100;100,400;100,300;400,300;400,400;400,100;400,200;100,200)");
 
   poly.assign_hull (pts, pts + sizeof (pts) / sizeof (pts[0]));
diff --git a/src/db/unit_tests/dbRegion.cc b/src/db/unit_tests/dbRegion.cc
index 2eeed72d6..8700ece97 100644
--- a/src/db/unit_tests/dbRegion.cc
+++ b/src/db/unit_tests/dbRegion.cc
@@ -122,7 +122,7 @@ TEST(1)
 
   r.set_merged_semantics (false);
   EXPECT_EQ (r.sized (10).to_string (), "(-10,-10;-10,60;60,60;60,-10);(40,40;40,110;110,110;110,40)");
-  EXPECT_EQ (r.sized (10, 20).to_string (), "(-10,-20;-10,70;60,70;60,-20);(40,30;40,120;110,120;110,30)");
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).to_string (), "(-10,-20;-10,70;60,70;60,-20);(40,30;40,120;110,120;110,30)");
   EXPECT_EQ (r.sized (10, 20, 0).to_string (), "(0,-20;-10,0;-10,50;0,70;50,70;60,50;60,0;50,-20);(50,30;40,50;40,100;50,120;100,120;110,100;110,50;100,30)");
   r.size (10, 20, 2);
   EXPECT_EQ (r.to_string (), "(-10,-20;-10,70;60,70;60,-20);(40,30;40,120;110,120;110,30)");
@@ -289,13 +289,13 @@ TEST(8)
   EXPECT_EQ (r.sized (10).to_string (), "(-10,-10;-10,210;110,210;110,-10)");
   EXPECT_EQ (r.sized (10).is_box (), true);
   EXPECT_EQ (r.sized (10).is_merged (), true);
-  EXPECT_EQ (r.sized (10, 20).to_string (), "(-10,-20;-10,220;110,220;110,-20)");
-  EXPECT_EQ (r.sized (10, 20).is_box (), true);
-  EXPECT_EQ (r.sized (10, 20).is_merged (), true);
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).to_string (), "(-10,-20;-10,220;110,220;110,-20)");
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).is_box (), true);
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).is_merged (), true);
 
   r.size (10);
   EXPECT_EQ (r.to_string (), "(-10,-10;-10,210;110,210;110,-10)");
-  r.size (10, 20);
+  r.size (db::Coord (10), db::Coord (20));
   EXPECT_EQ (r.to_string (), "(-20,-30;-20,230;120,230;120,-30)");
 }
 
@@ -307,9 +307,9 @@ TEST(9)
   EXPECT_EQ (r.sized (10).to_string (), "(-110,-110;-110,410;210,410;210,-110)");
   EXPECT_EQ (r.sized (10).is_box (), true);
   EXPECT_EQ (r.sized (10).is_merged (), false);
-  EXPECT_EQ (r.sized (10, 20).to_string (), "(-110,-120;-110,420;210,420;210,-120)");
-  EXPECT_EQ (r.sized (10, 20).is_box (), true);
-  EXPECT_EQ (r.sized (10, 20).is_merged (), false);
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).to_string (), "(-110,-120;-110,420;210,420;210,-120)");
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).is_box (), true);
+  EXPECT_EQ (r.sized (db::Coord (10), db::Coord (20)).is_merged (), false);
 }
 
 TEST(10a) 
@@ -1141,12 +1141,12 @@ TEST(27)
   db::Region r;
   r.insert (db::Box (db::Point (0, 0), db::Point (100, 200)));
 
-  EXPECT_EQ (r.sized (-10, -20).to_string (), "(10,20;10,180;90,180;90,20)");
-  EXPECT_EQ (r.sized (-50, -20).to_string (), "");
-  EXPECT_EQ (r.sized (-50, -100).to_string (), "");
-  EXPECT_EQ (r.sized (-55, -20).to_string (), "");
-  EXPECT_EQ (r.sized (-10, -105).to_string (), "");
-  EXPECT_EQ (r.sized (-55, -105).to_string (), "");
+  EXPECT_EQ (r.sized (db::Coord (-10), db::Coord (-20)).to_string (), "(10,20;10,180;90,180;90,20)");
+  EXPECT_EQ (r.sized (db::Coord (-50), db::Coord (-20)).to_string (), "");
+  EXPECT_EQ (r.sized (db::Coord (-50), db::Coord (-100)).to_string (), "");
+  EXPECT_EQ (r.sized (db::Coord (-55), db::Coord (-20)).to_string (), "");
+  EXPECT_EQ (r.sized (db::Coord (-10), db::Coord (-105)).to_string (), "");
+  EXPECT_EQ (r.sized (db::Coord (-55), db::Coord (-105)).to_string (), "");
 }
 
 TEST(28) 
@@ -1159,7 +1159,7 @@ TEST(28)
   r2.insert (db::Box (db::Point (100, 100), db::Point (200, 300)));
 
   EXPECT_EQ ((r1 & r2).to_string (), "");
-  EXPECT_EQ ((r1 & r2.sized (5, 5)).to_string (), "(95,95;95,200;100,200;100,95)");
+  EXPECT_EQ ((r1 & r2.sized (db::Coord (5), db::Coord (5))).to_string (), "(95,95;95,200;100,200;100,95)");
 }
 
 TEST(29) 
diff --git a/src/db/unit_tests/dbTrans.cc b/src/db/unit_tests/dbTrans.cc
index 399bfadb8..839b06aad 100644
--- a/src/db/unit_tests/dbTrans.cc
+++ b/src/db/unit_tests/dbTrans.cc
@@ -184,7 +184,7 @@ TEST(10)
   EXPECT_EQ (t.is_ortho (), true);
   EXPECT_EQ (t.to_string (), recomposed (t).to_string ());
 
-  t = db::DCplxTrans (db::ICplxTrans (db::disp_trans<int> (db::Vector (100, -256))));
+  t = db::DCplxTrans (db::ICplxTrans (db::disp_trans<db::Coord> (db::Vector (100, -256))));
   EXPECT_EQ (t.is_unity (), false);
   EXPECT_EQ (t.to_string (), "r0 *1 100,-256");
   EXPECT_EQ (t.is_ortho (), true);
@@ -202,7 +202,7 @@ TEST(10)
   EXPECT_EQ (t.to_string (), "r0 *1 -0.5,1.25");
   EXPECT_EQ (t.to_string (), recomposed (t).to_string ());
 
-  t = db::DCplxTrans (db::DTrans (db::simple_trans<int> (db::FTrans::m135, db::Vector (128, -256))));
+  t = db::DCplxTrans (db::DTrans (db::simple_trans<db::Coord> (db::FTrans::m135, db::Vector (128, -256))));
   EXPECT_EQ (t.is_unity (), false);
   EXPECT_EQ (t.to_string (), "m135 *1 128,-256");
   EXPECT_EQ (t.to_string (), recomposed (t).to_string ());
diff --git a/src/gsi/gsi/gsiTypes.cc b/src/gsi/gsi/gsiTypes.cc
index cf5d62f38..bffc48eb4 100644
--- a/src/gsi/gsi/gsiTypes.cc
+++ b/src/gsi/gsi/gsiTypes.cc
@@ -66,6 +66,10 @@ ArgType::to_string () const
     s += "long long"; break;
   case T_ulonglong:
     s += "unsigned long long"; break;
+#if defined(HAVE_64BIT_COORD)
+  case T_int128:
+    s += "int128"; break;
+#endif
   case T_double:
     s += "double"; break;
   case T_float:
diff --git a/src/lay/lay/layGSIHelpProvider.cc b/src/lay/lay/layGSIHelpProvider.cc
index 697a8c092..9a49c26db 100644
--- a/src/lay/lay/layGSIHelpProvider.cc
+++ b/src/lay/lay/layGSIHelpProvider.cc
@@ -577,6 +577,10 @@ type_to_s (const gsi::ArgType &a, bool linked, bool for_return)
     s += "unsigned short"; break;
   case gsi::T_int:
     s += "int"; break;
+#if defined(HAVE_64BIT_COORD)
+  case gsi::T_int128:
+    s += "int128"; break;
+#endif
   case gsi::T_uint:
     s += "unsigned int"; break;
   case gsi::T_long:
diff --git a/src/tl/tl/tl.pro b/src/tl/tl/tl.pro
index c71087b8e..48595c33c 100644
--- a/src/tl/tl/tl.pro
+++ b/src/tl/tl/tl.pro
@@ -42,7 +42,8 @@ SOURCES = \
     tlWebDAV.cc \
     tlArch.cc \
     tlCommandLineParser.cc \
-    tlUnitTest.cc
+    tlUnitTest.cc \
+    tlInt128Support.cc
 
 HEADERS = \
     tlAlgorithm.h \
@@ -90,7 +91,8 @@ HEADERS = \
     tlWebDAV.h \
     tlArch.h \
     tlCommandLineParser.h \
-    tlUnitTest.h
+    tlUnitTest.h \
+    tlInt128Support.h
 
 INCLUDEPATH =
 DEPENDPATH =
diff --git a/src/tl/tl/tlInt128Support.cc b/src/tl/tl/tlInt128Support.cc
new file mode 100644
index 000000000..a31b0ade3
--- /dev/null
+++ b/src/tl/tl/tlInt128Support.cc
@@ -0,0 +1,67 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2018 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#if defined(HAVE_64BIT_COORD)
+
+#include "tlInt128Support.h"
+
+namespace tl
+{
+
+std::string
+int128_to_string (__int128 x)
+{
+  std::string r;
+
+  //  this is the max. power of 10 that can be represented with __int128
+  __int128 m = (unsigned long long) 0x4b3b4ca85a86c47a;
+  m <<= 64;
+  m |= (unsigned long long) 0x98a224000000000;
+
+  if (x < 0) {
+    r = "-";
+    x = -x;
+  } else if (x == 0) {
+    return "0";
+  }
+
+  bool first = true;
+  while (m > 1) {
+    int d = 0;
+    while (x >= m) {
+      d += 1;
+      x -= m;
+    }
+    if (d > 0 || !first) {
+      r += char ('0' + d);
+      first = false;
+    }
+    m /= 10;
+  }
+
+  r += char('0' + int(x));
+  return r;
+}
+
+}
+
+#endif
diff --git a/src/tl/tl/tlInt128Support.h b/src/tl/tl/tlInt128Support.h
new file mode 100644
index 000000000..be69c2ab9
--- /dev/null
+++ b/src/tl/tl/tlInt128Support.h
@@ -0,0 +1,58 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2018 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#ifndef HDR_tlInt128Support
+#define HDR_tlInt128Support
+
+#if defined(HAVE_64BIT_COORD)
+
+#include "tlCommon.h"
+#include <inttypes.h>
+#include <ostream>
+
+namespace tl
+{
+  TL_PUBLIC std::string int128_to_string (__int128 x);
+}
+
+namespace std
+{
+
+  //  Provide an implementation for abs(__int128_t) if there isn't one
+  inline __int128 abs (__int128 x)
+  {
+    return x < 0 ? -x : x;
+  }
+
+  //  Provide ostream serialization for 128bit values
+  inline std::ostream &operator<< (std::ostream &os, __int128 x)
+  {
+    os << tl::int128_to_string (x);
+    return os;
+  }
+
+}
+
+#endif
+
+#endif
+
diff --git a/src/tl/tl/tlUnitTest.h b/src/tl/tl/tlUnitTest.h
index 7c1d149bb..66aea9fde 100644
--- a/src/tl/tl/tlUnitTest.h
+++ b/src/tl/tl/tlUnitTest.h
@@ -27,6 +27,7 @@
 #include "tlLog.h"
 #include "tlException.h"
 #include "tlString.h"
+#include "tlInt128Support.h"
 
 #include <string>
 #include <vector>
diff --git a/src/tl/unit_tests/tlInt128Support.cc b/src/tl/unit_tests/tlInt128Support.cc
new file mode 100644
index 000000000..64a2ed784
--- /dev/null
+++ b/src/tl/unit_tests/tlInt128Support.cc
@@ -0,0 +1,47 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2018 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#if defined(HAVE_64BIT_COORD)
+
+#include "tlInt128Support.h"
+#include "tlUnitTest.h"
+
+#include <cstdio>
+
+TEST(1) 
+{
+  EXPECT_EQ (tl::int128_to_string (__int128 (0)), "0");
+  EXPECT_EQ (tl::int128_to_string (__int128 (42)), "42");
+  EXPECT_EQ (tl::int128_to_string (__int128 (-42)), "-42");
+
+  __int128 x = 1;
+  for (int i = 0; i < 30; ++i) {
+     x *= 10;
+  }
+
+  EXPECT_EQ (tl::int128_to_string (x), "1000000000000000000000000000000");
+  EXPECT_EQ (tl::int128_to_string (-x), "-1000000000000000000000000000000");
+  EXPECT_EQ (tl::int128_to_string (x + 1), "1000000000000000000000000000001");
+  EXPECT_EQ (tl::int128_to_string (x - 1), "999999999999999999999999999999");
+}
+
+#endif
diff --git a/src/tl/unit_tests/unit_tests.pro b/src/tl/unit_tests/unit_tests.pro
index 59bcb5b09..1984e3fa0 100644
--- a/src/tl/unit_tests/unit_tests.pro
+++ b/src/tl/unit_tests/unit_tests.pro
@@ -32,6 +32,7 @@ SOURCES = \
   tlVariant.cc \
   tlWebDAV.cc \
   tlXMLParser.cc \
+    tlInt128Support.cc
 
 INCLUDEPATH += $$TL_INC
 DEPENDPATH += $$TL_INC