diff --git a/lib/loadImage.js b/lib/loadImage.js
index 8a3b686..c238a27 100644
--- a/lib/loadImage.js
+++ b/lib/loadImage.js
@@ -5,8 +5,6 @@ var path = require('path');
 var PNG = require('pngjs').PNG;
 var Promise = require('bluebird');
 
-var fsExtraReadFile = Promise.promisify(fsExtra.readFile);
-
 var defined = Cesium.defined;
 var WebGLConstants = Cesium.WebGLConstants;
 
@@ -23,7 +21,7 @@ module.exports = loadImage;
  * @private
  */
 function loadImage(imagePath, options) {
-    return fsExtraReadFile(imagePath)
+    return fsExtra.readFile(imagePath)
         .then(function(data) {
             var extension = path.extname(imagePath).toLowerCase();
 
diff --git a/lib/obj2gltf.js b/lib/obj2gltf.js
index 260df96..33f6e89 100644
--- a/lib/obj2gltf.js
+++ b/lib/obj2gltf.js
@@ -10,8 +10,6 @@ var createGltf = require('./createGltf');
 var loadObj = require('./loadObj');
 var writeUris = require('./writeUris');
 
-var fsExtraOutputJson = Promise.promisify(fsExtra.outputJson);
-
 var defaultValue = Cesium.defaultValue;
 var defined = Cesium.defined;
 var DeveloperError = Cesium.DeveloperError;
@@ -121,7 +119,7 @@ function obj2gltf(objPath, gltfPath, options) {
         })
         .then(function(gltf) {
             if (bypassPipeline) {
-                return obj2gltf._outputJson(gltfPath, gltf);
+                return fsExtra.outputJson(gltfPath, gltf);
             } else {
                 return GltfPipeline.processJSONToDisk(gltf, gltfPath, pipelineOptions);
             }
@@ -237,13 +235,6 @@ obj2gltf.defaults = {
     }
 };
 
-/**
- * Exposed for testing
- *
- * @private
- */
-obj2gltf._outputJson = fsExtraOutputJson;
-
 /**
  * Exposed for testing
  *
diff --git a/lib/writeUris.js b/lib/writeUris.js
index 1a578fd..5987a72 100644
--- a/lib/writeUris.js
+++ b/lib/writeUris.js
@@ -5,8 +5,6 @@ var mime = require('mime');
 var path = require('path');
 var Promise = require('bluebird');
 
-var fsExtraOutputFile = Promise.promisify(fsExtra.outputFile);
-
 var RuntimeError = Cesium.RuntimeError;
 
 module.exports = writeUris;
@@ -88,7 +86,7 @@ function writeSeparateBuffer(gltf, resourcesDirectory, name) {
     var bufferUri = name + '.bin';
     buffer.uri = bufferUri;
     var bufferPath = path.join(resourcesDirectory, bufferUri);
-    return writeUris._outputFile(bufferPath, source);
+    return fsExtra.outputFile(bufferPath, source);
 }
 
 function writeSeparateTextures(gltf, resourcesDirectory) {
@@ -99,7 +97,7 @@ function writeSeparateTextures(gltf, resourcesDirectory) {
         var imageUri = image.name + extras.extension;
         image.uri = imageUri;
         var imagePath = path.join(resourcesDirectory, imageUri);
-        return writeUris._outputFile(imagePath, extras.source);
+        return fsExtra.outputFile(imagePath, extras.source);
     }, {concurrency : 10});
 }
 
@@ -119,10 +117,3 @@ function writeEmbeddedTextures(gltf) {
         }
     }
 }
-
-/**
- * Exposed for testing.
- *
- * @private
- */
-writeUris._outputFile = fsExtraOutputFile;
diff --git a/package.json b/package.json
index 338fc7c..0d37800 100644
--- a/package.json
+++ b/package.json
@@ -29,12 +29,12 @@
     "bluebird": "^3.4.7",
     "cesium": "^1.31.0",
     "event-stream": "^3.3.4",
-    "fs-extra": "^2.0.0",
+    "fs-extra": "^3.0.1",
     "gltf-pipeline": "^0.1.0-alpha11",
     "mime": "^1.3.4",
     "pngjs": "^3.0.1",
     "uuid": "^3.0.1",
-    "yargs": "^7.0.1"
+    "yargs": "^8.0.1"
   },
   "devDependencies": {
     "coveralls": "^2.12.0",
@@ -42,7 +42,7 @@
     "gulp-jshint": "^2.0.4",
     "istanbul": "^0.4.5",
     "jasmine": "^2.5.3",
-    "jasmine-spec-reporter": "^3.2.0",
+    "jasmine-spec-reporter": "^4.1.0",
     "jsdoc": "^3.4.3",
     "jshint": "^2.9.4",
     "jshint-stylish": "^2.2.1",
diff --git a/specs/lib/createGltfSpec.js b/specs/lib/createGltfSpec.js
index b90d5bc..1e750ee 100644
--- a/specs/lib/createGltfSpec.js
+++ b/specs/lib/createGltfSpec.js
@@ -13,8 +13,6 @@ var writeUris = require('../../lib/writeUris');
 var clone = Cesium.clone;
 var WebGLConstants = Cesium.WebGLConstants;
 
-var fsExtraReadJson = Promise.promisify(fsExtra.readJson);
-
 var boxObjUrl = 'specs/data/box/box.obj';
 var groupObjUrl = 'specs/data/box-objects-groups-materials/box-objects-groups-materials.obj';
 var boxGltfUrl = 'specs/data/box/box.gltf';
@@ -49,11 +47,11 @@ describe('createGltf', function() {
                 .then(function(data) {
                     groupObjData = data;
                 }),
-            fsExtraReadJson(boxGltfUrl)
+            fsExtra.readJson(boxGltfUrl)
                 .then(function(gltf) {
                     boxGltf = gltf;
                 }),
-            fsExtraReadJson(groupGltfUrl)
+            fsExtra.readJson(groupGltfUrl)
                 .then(function(gltf) {
                     groupGltf = gltf;
                 }),
diff --git a/specs/lib/obj2gltfSpec.js b/specs/lib/obj2gltfSpec.js
index a25ca3f..d2aa73d 100644
--- a/specs/lib/obj2gltfSpec.js
+++ b/specs/lib/obj2gltfSpec.js
@@ -19,8 +19,8 @@ describe('obj2gltf', function() {
         expect(obj2gltf._getTempDirectory()).toContain(os.tmpdir());
         tempDirectory = path.join(os.tmpdir(), 'testPath');
         spyOn(obj2gltf, '_getTempDirectory').and.returnValue(tempDirectory);
-        spyOn(obj2gltf, '_outputJson');
-        spyOn(writeUris, '_outputFile');
+        spyOn(fsExtra, 'outputJson');
+        spyOn(fsExtra, 'outputFile');
         spyOn(fsExtra, 'remove');
     });
 
@@ -100,7 +100,7 @@ describe('obj2gltf', function() {
                     textureCompressionOptions : textureCompressionOptions,
                     preserve : false
                 });
-                expect(writeUris._outputFile.calls.count()).toBe(2); // Saves out .png and .bin
+                expect(fsExtra.outputFile.calls.count()).toBe(2); // Saves out .png and .bin
             }), done).toResolve();
     });
 
@@ -119,7 +119,7 @@ describe('obj2gltf', function() {
         };
         expect(obj2gltf(objPath, gltfPath, options)
             .then(function() {
-                expect(obj2gltf._outputJson).toHaveBeenCalled();
+                expect(fsExtra.outputJson).toHaveBeenCalled();
                 expect(GltfPipeline.processJSONToDisk).not.toHaveBeenCalled();
             }), done).toResolve();
     });