diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8d87b1d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+node_modules/*
diff --git a/index.js b/index.js
index d02c6d9..b7e4f17 100644
--- a/index.js
+++ b/index.js
@@ -1,9 +1,4 @@
-// look here for help http://svn.osgeo.org/grass/grass/branches/releasebranch_6_4/vector/v.overlay/main.c
-//must be array of polygons
-
-// depend on jsts for now https://github.com/bjornharrtell/jsts/blob/master/examples/overlay.html
-
-var jsts = require('jsts');
+var gh = require('gh-clipping-algorithm');
 
 /**
  * Takes two {@link Polygon|polygons} and returns a combined polygon. If the input polygons are not contiguous, this function returns a {@link MultiPolygon} feature.
@@ -58,16 +53,37 @@ var jsts = require('jsts');
  * //=union
  */
 module.exports = function(poly1, poly2) {
-  var reader = new jsts.io.GeoJSONReader();
-  var a = reader.read(JSON.stringify(poly1.geometry));
-  var b = reader.read(JSON.stringify(poly2.geometry));
-  var union = a.union(b);
-  var parser = new jsts.io.GeoJSONParser();
+  // console.log(poly1);
+  var a = poly1.coordinates ? poly1.coordinates : poly1.geometry.coordinates;
+  var b = poly2.coordinates ? poly2.coordinates : poly2.geometry.coordinates;
+  var u = gh.union(a, b);
 
-  union = parser.write(union);
-  return {
-    type: 'Feature',
-    geometry: union,
-    properties: poly1.properties
+  var feature = {
+    "type": "Feature",
+    "properties": {},
+    "geometry": {}
   };
+
+  if (!u || u.length == 0) {
+    return undefined;
+  }
+
+  if (gh.utils.isMultiPolygon(u)) {
+    if (u.length > 1) {
+      feature.geometry.type = "MultiPolygon";
+      feature.geometry.coordinates = u;
+    } else {
+      feature.geometry.type = "Polygon";
+      feature.geometry.coordinates = u[0];
+    }
+  } else if (gh.utils.isPolygon(u)) {
+    feature.geometry.type = "Polygon";
+    feature.geometry.coordinates = u;
+  }
+
+  if (poly1.properties) {
+    feature.properties = poly1.properties;
+  }
+
+  return feature;
 };
diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
deleted file mode 100644
index b334988..0000000
--- a/npm-shrinkwrap.json
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-  "name": "turf-union",
-  "version": "1.0.2",
-  "dependencies": {
-    "jsts": {
-      "version": "0.15.0",
-      "from": "jsts@>=0.15.0 <0.16.0",
-      "resolved": "https://registry.npmjs.org/jsts/-/jsts-0.15.0.tgz",
-      "dependencies": {
-        "javascript.util": {
-          "version": "0.12.5",
-          "resolved": "https://registry.npmjs.org/javascript.util/-/javascript.util-0.12.5.tgz"
-        }
-      }
-    }
-  }
-}
diff --git a/package.json b/package.json
index 3c9a2be..b93c211 100644
--- a/package.json
+++ b/package.json
@@ -26,9 +26,10 @@
     "glob": "~4.3.5",
     "tape": "~3.5.0",
     "dox": "^0.6.1",
-    "doxme": "^1.4.3"
+    "doxme": "^1.4.3",
+    "geojson-equality": "^0.1.4"
   },
   "dependencies": {
-    "jsts": "~0.15.0"
+    "gh-clipping-algorithm": "^0.*"
   }
 }
diff --git a/test/union.js b/test/union.js
index dd636de..6a92e0c 100644
--- a/test/union.js
+++ b/test/union.js
@@ -1,7 +1,8 @@
 var union = require('../'),
   test = require('tape'),
   glob = require('glob'),
-  fs = require('fs');
+  fs = require('fs'),
+  equal = new(require('geojson-equality'));
 
 var REGEN = false;
 
@@ -10,7 +11,7 @@ test('union', function(t){
       var fcs = JSON.parse(fs.readFileSync(input));
       var output = union(fcs[0].features[0], fcs[1].features[0]);
       if (REGEN) fs.writeFileSync(input.replace('/in/', '/out/'), JSON.stringify(output));
-      t.deepEqual(output, JSON.parse(fs.readFileSync(input.replace('/in/', '/out/'))), input);
+      t.ok(equal.compare(output, JSON.parse(fs.readFileSync(input.replace('/in/', '/out/')))), input);
   });
   t.end();
 });