diff --git a/demo/js/bundle.js b/demo/js/bundle.js
index 5d07547..f5eff76 100644
--- a/demo/js/bundle.js
+++ b/demo/js/bundle.js
@@ -1781,6 +1781,8 @@
 
   //var martinez = require('../../dist/martinez.min');
 
+  window.martinez = boolean;
+
   var mode = window.location.hash.substring(1);
   var path = '../test/fixtures/';
   var file;
@@ -1849,6 +1851,9 @@
     case 'rectangles':
       file = 'rectangles.geojson';
       break;
+    case 'boxes_overlap':
+      file = 'boxes_overlap.geojson';
+      break;
     default:
       file = 'hole_hole.geojson';
       break;
@@ -1897,6 +1902,7 @@
     fetch(path)
       .then(function (r) { return r.json(); })
       .then(function (json) {
+          window.data = json;
           drawnItems.addData(json);
           map.fitBounds(drawnItems.getBounds().pad(0.05), { animate: false });
       });
diff --git a/demo/js/index.js b/demo/js/index.js
index b709130..f745154 100644
--- a/demo/js/index.js
+++ b/demo/js/index.js
@@ -4,6 +4,8 @@ import './booleanopcontrol';
 import martinez from '../../src/index';
 //var martinez = require('../../dist/martinez.min');
 
+window.martinez = martinez;
+
 let mode = window.location.hash.substring(1);
 let path = '../test/fixtures/';
 const ext  = '.geojson';
@@ -79,6 +81,9 @@ switch (mode) {
   case 'rectangles':
     file = 'rectangles.geojson';
     break;
+  case 'boxes_overlap':
+    file = 'boxes_overlap.geojson';
+    break;
   default:
     file = 'hole_hole.geojson';
     break;
@@ -127,6 +132,7 @@ function loadData(path) {
   fetch(path)
     .then((r) => r.json())
     .then((json) => {
+        window.data = json;
         drawnItems.addData(json);
         map.fitBounds(drawnItems.getBounds().pad(0.05), { animate: false });
     });
diff --git a/dist/martinez.umd.js b/dist/martinez.umd.js
index ec5578c..5f77308 100644
--- a/dist/martinez.umd.js
+++ b/dist/martinez.umd.js
@@ -1,5 +1,5 @@
 /**
- * martinez v0.4.1
+ * martinez v0.4.0
  * Martinez polygon clipping algorithm, does boolean operation on polygons (multipolygons, polygons with holes etc): intersection, union, difference, xor
  *
  * @author Alex Milevski <info@w8r.name>
diff --git a/test/edge_cases.test.js b/test/edge_cases.test.js
index 9c12ba1..24e3322 100644
--- a/test/edge_cases.test.js
+++ b/test/edge_cases.test.js
@@ -438,5 +438,39 @@ tap.test('Edge cases', (main) => {
     t.end();
   });
 
+
+  main.test('issue #80', (t) => {
+    const shapes   = load.sync(path.join(__dirname, 'fixtures', 'boxes_overlap.geojson'));
+    const subject  = shapes.features[0];
+    const clipping = shapes.features[1];
+
+    console.log(shapes);
+
+
+    t.test('difference', (t) => {
+      const result = martinez.diff(
+        subject.geometry.coordinates,
+        clipping.geometry.coordinates
+      );
+      t.deepEqual(result, [[[
+        [10, 10],
+        [20, 10],
+        [20, 80],
+        [10, 80],
+        [10, 10]
+      ]], [[
+        [30, 10],
+        [80, 10],
+        [80, 80],
+        [30, 80],
+        [30, 10]
+      ]]]);
+
+      t.end();
+    });
+
+    t.end();
+  });
+
   main.end();
 });
diff --git a/test/fixtures/boxes_overlap.geojson b/test/fixtures/boxes_overlap.geojson
new file mode 100644
index 0000000..9906f50
--- /dev/null
+++ b/test/fixtures/boxes_overlap.geojson
@@ -0,0 +1,65 @@
+{
+  "type": "FeatureCollection",
+  "features": [
+    {
+      "type": "Feature",
+      "geometry": {
+        "type": "Polygon",
+        "coordinates": [
+          [
+            [
+              10,
+              10
+            ],
+            [
+              80,
+              10
+            ],
+            [
+              80,
+              80
+            ],
+            [
+              10,
+              80
+            ],
+            [
+              10,
+              10
+            ]
+          ]
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "geometry": {
+        "type": "Polygon",
+        "coordinates": [
+          [
+            [
+              20,
+              10
+            ],
+            [
+              30,
+              10
+            ],
+            [
+              30,
+              80
+            ],
+            [
+              20,
+              80
+            ],
+            [
+              20,
+              10
+            ]
+          ]
+        ]
+      }
+    }
+  ]
+}