diff --git a/docs/users.rst b/docs/users.rst
index 5e02f77bad..eee8a410ae 100644
--- a/docs/users.rst
+++ b/docs/users.rst
@@ -23,7 +23,7 @@ list of libraries used by GeoJS.
     +---------------------------+------------+---------------------------+
     | Library                   | Version    | Component                 |
     +===========================+============+===========================+
-    | `proj4`_                  | 2.3        | Core                      |
+    | `proj4`_                  | 2.4        | Core                      |
     +---------------------------+------------+---------------------------+
     | `GL matrix`_              | 2.1        | Core, GL renderer         |
     +---------------------------+------------+---------------------------+
diff --git a/package-lock.json b/package-lock.json
index 65114b8c9f..f8eae414a1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -249,7 +249,7 @@
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@@ -723,7 +723,7 @@
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@@ -2078,7 +2078,7 @@
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+        "caniuse-db": "1.0.30000870",
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@@ -2192,12 +2192,12 @@
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+        "mime-types": "2.1.19",
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@@ -2328,15 +2328,15 @@
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@@ -2692,9 +2692,9 @@
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+      "version": "5.39.2",
+      "resolved": "https://registry.npmjs.org/codemirror/-/codemirror-5.39.2.tgz",
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@@ -3667,7 +3667,7 @@
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@@ -4518,9 +4518,9 @@
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@@ -7592,13 +7592,13 @@
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@@ -7814,13 +7814,13 @@
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@@ -8442,7 +8442,7 @@
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@@ -8653,7 +8653,7 @@
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@@ -8667,9 +8667,9 @@
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@@ -9176,9 +9176,9 @@
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@@ -10882,7 +10882,7 @@
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@@ -12072,15 +12073,15 @@
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@@ -15293,7 +15294,7 @@
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@@ -16042,6 +16043,12 @@
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@@ -16440,7 +16447,7 @@
         "shelljs": "0.8.2",
         "text-table": "0.2.0",
         "through2": "2.0.3",
-        "yeoman-environment": "2.3.0"
+        "yeoman-environment": "2.3.1"
       },
       "dependencies": {
         "ansi-styles": {
diff --git a/package.json b/package.json
index cd2fa4365b..2ed3f2ebf7 100644
--- a/package.json
+++ b/package.json
@@ -70,7 +70,7 @@
     "nib": "^1.1.2",
     "pako": "^1.0.6",
     "phantomjs-prebuilt": "^2.1.5",
-    "proj4": "2.3.16",
+    "proj4": "^2.4.4",
     "pug": "^2.0.3",
     "pug-lint": "^2.4.0",
     "pug-loader": "^2.4.0",
diff --git a/src/transform.js b/src/transform.js
index 472cb9a11b..30a5d5e330 100644
--- a/src/transform.js
+++ b/src/transform.js
@@ -1,9 +1,10 @@
 var proj4 = require('proj4');
-/* These projections exist in proj4 but aren't included by default. */
-proj4.Proj.projections.add(require('proj4/projections/equi'));
-proj4.Proj.projections.add(require('proj4/projections/gauss'));
-proj4.Proj.projections.add(require('proj4/projections/gstmerc'));
-proj4.Proj.projections.add(require('proj4/projections/ortho'));
+proj4 = proj4.__esModule ? proj4.default : proj4;
+/* Ensure all projections in proj4 are included. */
+var projections = require.context('proj4/projections', true, /.*\.js$/);
+projections.keys().forEach(function (key) {
+  proj4.Proj.projections.add(projections(key));
+});
 var util = require('./util');
 
 /**
@@ -254,7 +255,7 @@ transform.transformCoordinates = function (
 
   var trans = transform({source: srcPrj, target: tgtPrj}), output;
   if (util.isObject(coordinates) && 'x' in coordinates && 'y' in coordinates) {
-    output = trans.forward({x: coordinates.x, y: coordinates.y, z: coordinates.z || 0});
+    output = trans.forward({x: +coordinates.x, y: +coordinates.y, z: +coordinates.z || 0});
     if ('z' in coordinates) {
       return output;
     }
@@ -263,7 +264,7 @@ transform.transformCoordinates = function (
   if (Array.isArray(coordinates) && coordinates.length === 1 &&
       util.isObject(coordinates[0]) && 'x' in coordinates[0] &&
       'y' in coordinates[0]) {
-    output = trans.forward({x: coordinates[0].x, y: coordinates[0].y, z: coordinates[0].z || 0});
+    output = trans.forward({x: +coordinates[0].x, y: +coordinates[0].y, z: +coordinates[0].z || 0});
     if ('z' in coordinates[0]) {
       return [output];
     }
@@ -298,23 +299,23 @@ transform.transformCoordinatesArray = function (trans, coordinates, numberOfComp
     if (Array.isArray(coordinates[0])) {
       if (coordinates[0].length === 2) {
         xAcc = function (index) {
-          return coordinates[index][0];
+          return +coordinates[index][0];
         };
         yAcc = function (index) {
-          return coordinates[index][1];
+          return +coordinates[index][1];
         };
         writer = function (index, x, y) {
           output[index] = [x, y];
         };
       } else if (coordinates[0].length === 3) {
         xAcc = function (index) {
-          return coordinates[index][0];
+          return +coordinates[index][0];
         };
         yAcc = function (index) {
-          return coordinates[index][1];
+          return +coordinates[index][1];
         };
         zAcc = function (index) {
-          return coordinates[index][2];
+          return +coordinates[index][2];
         };
         writer = function (index, x, y, z) {
           output[index] = [x, y, z];
@@ -327,10 +328,10 @@ transform.transformCoordinatesArray = function (trans, coordinates, numberOfComp
         offset = 2;
 
         xAcc = function (index) {
-          return coordinates[index * offset];
+          return +coordinates[index * offset];
         };
         yAcc = function (index) {
-          return coordinates[index * offset + 1];
+          return +coordinates[index * offset + 1];
         };
         writer = function (index, x, y) {
           output[index] = x;
@@ -340,13 +341,13 @@ transform.transformCoordinatesArray = function (trans, coordinates, numberOfComp
         offset = 3;
 
         xAcc = function (index) {
-          return coordinates[index * offset];
+          return +coordinates[index * offset];
         };
         yAcc = function (index) {
-          return coordinates[index * offset + 1];
+          return +coordinates[index * offset + 1];
         };
         zAcc = function (index) {
-          return coordinates[index * offset + 2];
+          return +coordinates[index * offset + 2];
         };
         writer = function (index, x, y, z) {
           output[index] = x;
@@ -358,10 +359,10 @@ transform.transformCoordinatesArray = function (trans, coordinates, numberOfComp
           offset = numberOfComponents;
 
           xAcc = function (index) {
-            return coordinates[index];
+            return +coordinates[index];
           };
           yAcc = function (index) {
-            return coordinates[index + 1];
+            return +coordinates[index + 1];
           };
           if (numberOfComponents === 2) {
             writer = function (index, x, y) {
@@ -370,7 +371,7 @@ transform.transformCoordinatesArray = function (trans, coordinates, numberOfComp
             };
           } else {
             zAcc = function (index) {
-              return coordinates[index + 2];
+              return +coordinates[index + 2];
             };
             writer = function (index, x, y, z) {
               output[index] = x;
@@ -393,15 +394,15 @@ transform.transformCoordinatesArray = function (trans, coordinates, numberOfComp
         'x' in coordinates[0] &&
         'y' in coordinates[0]) {
       xAcc = function (index) {
-        return coordinates[index].x;
+        return +coordinates[index].x;
       };
       yAcc = function (index) {
-        return coordinates[index].y;
+        return +coordinates[index].y;
       };
 
       if ('z' in coordinates[0]) {
         zAcc = function (index) {
-          return coordinates[index].z;
+          return +coordinates[index].z;
         };
         writer = function (index, x, y, z) {
           output[i] = {x: x, y: y, z: z};
diff --git a/src/util/index.js b/src/util/index.js
index ba39ca3e8a..4d7751051f 100644
--- a/src/util/index.js
+++ b/src/util/index.js
@@ -1,5 +1,6 @@
 var $ = require('jquery');
 var proj4 = require('proj4');
+proj4 = proj4.__esModule ? proj4.default : proj4;
 
 var throttle = require('./throttle');
 var mockVGL = require('./mockVGL');
diff --git a/tests/cases/annotationLayer.js b/tests/cases/annotationLayer.js
index 6e74cad68c..2cec9e4054 100644
--- a/tests/cases/annotationLayer.js
+++ b/tests/cases/annotationLayer.js
@@ -156,6 +156,15 @@ describe('geo.annotationLayer', function () {
         corners: [{x: 0, y: 0}, {x: 1, y: 0}, {x: 1, y: 1}, {x: 0, y: 1}]});
       layer.addAnnotation(rect, map.gcs());
       expect(layer.annotations()[1]._coordinates()[1]).toEqual({x: 1, y: 0});
+      /* Change the map input gcs to the main gcs and the coordinates won't be
+       * altered. */
+      map.ingcs(map.gcs());
+      layer.removeAnnotation(rect);
+      rect = geo.annotation.rectangleAnnotation({
+        layer: layer,
+        corners: [{x: 0, y: 0}, {x: 1, y: 0}, {x: 1, y: 1}, {x: 0, y: 1}]});
+      layer.addAnnotation(rect);
+      expect(layer.annotations()[1]._coordinates()[1]).toEqual({x: 1, y: 0});
     });
     it('annotationById', function () {
       expect(layer.annotationById()).toBe(undefined);
@@ -192,19 +201,6 @@ describe('geo.annotationLayer', function () {
       expect(removeAnnotationEvent).toBe(3);
       expect(layer.annotations().length).toBe(1);
     });
-    it('displayDistance', function () {
-      var c1 = {x: 100, y: 80},
-          c2 = map.displayToGcs({x: 105, y: 84}),        /* ingcs */
-          c3 = map.displayToGcs({x: 107, y: 88}, null);  /* gcs */
-      expect(layer.displayDistance(c1, 'display', c2)).toBeCloseTo(6.40, 2);
-      expect(layer.displayDistance(c1, 'display', c2, 'EPSG:4326')).toBeCloseTo(6.40, 2);
-      expect(layer.displayDistance(c1, 'display', c3, null)).toBeCloseTo(10.63, 2);
-      expect(layer.displayDistance(c1, 'display', c3, 'EPSG:3857')).toBeCloseTo(10.63, 2);
-      expect(layer.displayDistance(c2, undefined, c1, 'display')).toBeCloseTo(6.40, 2);
-      expect(layer.displayDistance(c2, undefined, c3, null)).toBeCloseTo(4.47, 2);
-      expect(layer.displayDistance(c3, null, c1, 'display')).toBeCloseTo(10.63, 2);
-      expect(layer.displayDistance(c3, null, c2)).toBeCloseTo(4.47, 2);
-    });
     it('geojson', function () {
       layer.removeAllAnnotations();
       layer.addAnnotation(poly);
@@ -330,6 +326,20 @@ describe('geo.annotationLayer', function () {
       expect(layer.validateAttribute(0.5, 'text')).toBe('0.5');
       expect(layer.validateAttribute('value', 'text')).toBe('value');
     });
+    it('displayDistance', function () {
+      map.ingcs('EPSG:4326');
+      var c1 = {x: 100, y: 80},
+          c2 = map.displayToGcs({x: 105, y: 84}),        /* ingcs */
+          c3 = map.displayToGcs({x: 107, y: 88}, null);  /* gcs */
+      expect(layer.displayDistance(c1, 'display', c2)).toBeCloseTo(6.40, 2);
+      expect(layer.displayDistance(c1, 'display', c2, 'EPSG:4326')).toBeCloseTo(6.40, 2);
+      expect(layer.displayDistance(c1, 'display', c3, null)).toBeCloseTo(10.63, 2);
+      expect(layer.displayDistance(c1, 'display', c3, 'EPSG:3857')).toBeCloseTo(10.63, 2);
+      expect(layer.displayDistance(c2, undefined, c1, 'display')).toBeCloseTo(6.40, 2);
+      expect(layer.displayDistance(c2, undefined, c3, null)).toBeCloseTo(4.47, 2);
+      expect(layer.displayDistance(c3, null, c1, 'display')).toBeCloseTo(10.63, 2);
+      expect(layer.displayDistance(c3, null, c2)).toBeCloseTo(4.47, 2);
+    });
   });
   describe('Private utility functions', function () {
     var map, layer, point, rect, rect2, editActionEvent = 0;
diff --git a/tests/cases/transform.js b/tests/cases/transform.js
index 9d9db63b03..3fc106e60a 100644
--- a/tests/cases/transform.js
+++ b/tests/cases/transform.js
@@ -236,6 +236,10 @@ describe('geo.transform', function () {
       expect(closeToEqual(geo.transform.transformCoordinates(source, target, {x: 1, y: 2}), {x: 1, y: -2})).toBe(true);
       expect(closeToEqual(geo.transform.transformCoordinates(source, target, {x: 3, y: 4, z: 5}), {x: 3, y: -4, z: 5})).toBe(true);
     });
+    it('coordinate format - single object with strings', function () {
+      expect(closeToEqual(geo.transform.transformCoordinates(source, target, {x: '1', y: '2'}), {x: 1, y: -2})).toBe(true);
+      expect(closeToEqual(geo.transform.transformCoordinates(source, target, {x: '3', y: '4', z: '5'}), {x: 3, y: -4, z: 5})).toBe(true);
+    });
     it('empty array', function () {
       var res = geo.transform.transformCoordinates(source, target, []);
       expect(res instanceof Array).toBe(true);
@@ -247,16 +251,22 @@ describe('geo.transform', function () {
       expect(res instanceof Array).toBe(true);
       expect(res.length).toBe(1);
       expect(closeToEqual(res[0], {x: 1, y: -2})).toBe(true);
+      res = geo.transform.transformCoordinates(source, target, [{x: '1', y: '2'}]);
+      expect(closeToEqual(res[0], {x: 1, y: -2})).toBe(true);
       res = geo.transform.transformCoordinates(source, target, [{x: 3, y: 4, z: 5}]);
       expect(res instanceof Array).toBe(true);
       expect(res.length).toBe(1);
       expect(closeToEqual(res[0], {x: 3, y: -4, z: 5})).toBe(true);
+      res = geo.transform.transformCoordinates(source, target, [{x: '3', y: '4', z: '5'}]);
+      expect(closeToEqual(res[0], {x: 3, y: -4, z: 5})).toBe(true);
     });
     it('coordinate format - single array', function () {
       expect(closeToArray(geo.transform.transformCoordinates(source, target, [1, 2]), [1, -2])).toBe(true);
       expect(closeToArray(geo.transform.transformCoordinates(source, target, [3, 4, 5]), [3, -4, 5])).toBe(true);
       expect(closeToArray(geo.transform.transformCoordinates(source, target, [1, 2, 3, 4, 5, 6], 2), [1, -2, 3, -4, 5, -6])).toBe(true);
       expect(closeToArray(geo.transform.transformCoordinates(source, target, [1, 2, 3, 4, 5, 6], 3), [1, -2, 3, 4, -5, 6])).toBe(true);
+      expect(closeToArray(geo.transform.transformCoordinates(source, target, ['1', '2']), [1, -2])).toBe(true);
+      expect(closeToArray(geo.transform.transformCoordinates(source, target, ['3', '4', '5']), [3, -4, 5])).toBe(true);
     });
     it('coordinate format - array of arrays', function () {
       var res;
@@ -265,10 +275,14 @@ describe('geo.transform', function () {
       expect(closeToArray(res[0], [1, -2])).toBe(true);
       expect(closeToArray(res[1], [3, -4])).toBe(true);
       expect(closeToArray(res[2], [5, -6])).toBe(true);
+      res = geo.transform.transformCoordinates(source, target, [['1', '2'], ['3', '4'], ['5', '6']]);
+      expect(closeToArray(res[0], [1, -2])).toBe(true);
       res = geo.transform.transformCoordinates(source, target, [[1, 2, 3], [4, 5, 6]]);
       expect(res.length).toBe(2);
       expect(closeToArray(res[0], [1, -2, 3])).toBe(true);
       expect(closeToArray(res[1], [4, -5, 6])).toBe(true);
+      res = geo.transform.transformCoordinates(source, target, [['1', '2', '3'], ['4', '5', '6']]);
+      expect(closeToArray(res[0], [1, -2, 3])).toBe(true);
     });
     it('coordinate format - array of objects', function () {
       var res;
@@ -277,10 +291,14 @@ describe('geo.transform', function () {
       expect(closeToEqual(res[0], {x: 1, y: -2})).toBe(true);
       expect(closeToEqual(res[1], {x: 3, y: -4})).toBe(true);
       expect(closeToEqual(res[2], {x: 5, y: -6})).toBe(true);
+      res = geo.transform.transformCoordinates(source, target, [{x: '1', y: '2'}, {x: '3', y: '4'}, {x: '5', y: '6'}]);
+      expect(closeToEqual(res[0], {x: 1, y: -2})).toBe(true);
       res = geo.transform.transformCoordinates(source, target, [{x: 1, y: 2, z: 3}, {x: 4, y: 5, z: 6}]);
       expect(res.length).toBe(2);
       expect(closeToEqual(res[0], {x: 1, y: -2, z: 3})).toBe(true);
       expect(closeToEqual(res[1], {x: 4, y: -5, z: 6})).toBe(true);
+      res = geo.transform.transformCoordinates(source, target, [{x: '1', y: '2', z: '3'}, {x: '4', y: '5', z: '6'}]);
+      expect(closeToEqual(res[0], {x: 1, y: -2, z: 3})).toBe(true);
     });
   });