diff --git a/package-lock.json b/package-lock.json
index a989faf..4fbb263 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -3946,12 +3946,14 @@
 				"balanced-match": {
 					"version": "1.0.0",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"brace-expansion": {
 					"version": "1.1.11",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"balanced-match": "^1.0.0",
 						"concat-map": "0.0.1"
@@ -3966,17 +3968,20 @@
 				"code-point-at": {
 					"version": "1.1.0",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"concat-map": {
 					"version": "0.0.1",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"console-control-strings": {
 					"version": "1.1.0",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"core-util-is": {
 					"version": "1.0.2",
@@ -4093,7 +4098,8 @@
 				"inherits": {
 					"version": "2.0.3",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"ini": {
 					"version": "1.3.5",
@@ -4105,6 +4111,7 @@
 					"version": "1.0.0",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"number-is-nan": "^1.0.0"
 					}
@@ -4119,6 +4126,7 @@
 					"version": "3.0.4",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"brace-expansion": "^1.1.7"
 					}
@@ -4126,12 +4134,14 @@
 				"minimist": {
 					"version": "0.0.8",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"minipass": {
 					"version": "2.2.4",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"safe-buffer": "^5.1.1",
 						"yallist": "^3.0.0"
@@ -4150,6 +4160,7 @@
 					"version": "0.5.1",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"minimist": "0.0.8"
 					}
@@ -4237,7 +4248,8 @@
 				"number-is-nan": {
 					"version": "1.0.1",
 					"bundled": true,
-					"dev": true
+					"dev": true,
+					"optional": true
 				},
 				"object-assign": {
 					"version": "4.1.1",
@@ -4249,6 +4261,7 @@
 					"version": "1.4.0",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"wrappy": "1"
 					}
@@ -4370,6 +4383,7 @@
 					"version": "1.0.2",
 					"bundled": true,
 					"dev": true,
+					"optional": true,
 					"requires": {
 						"code-point-at": "^1.0.0",
 						"is-fullwidth-code-point": "^1.0.0",
@@ -5822,7 +5836,6 @@
 							"version": "1.1.11",
 							"bundled": true,
 							"dev": true,
-							"optional": true,
 							"requires": {
 								"balanced-match": "^1.0.0",
 								"concat-map": "0.0.1"
@@ -5991,7 +6004,6 @@
 							"version": "3.0.4",
 							"bundled": true,
 							"dev": true,
-							"optional": true,
 							"requires": {
 								"brace-expansion": "^1.1.7"
 							}
@@ -11266,7 +11278,6 @@
 							"version": "1.1.11",
 							"bundled": true,
 							"dev": true,
-							"optional": true,
 							"requires": {
 								"balanced-match": "^1.0.0",
 								"concat-map": "0.0.1"
@@ -11435,7 +11446,6 @@
 							"version": "3.0.4",
 							"bundled": true,
 							"dev": true,
-							"optional": true,
 							"requires": {
 								"brace-expansion": "^1.1.7"
 							}
diff --git a/package.json b/package.json
index f61b9c1..bd4d8eb 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
 	"typings": "types/skinview3d.d.ts",
 	"scripts": {
 		"build": "rollup -c tools/rollup.module.js && rollup -c tools/rollup.browser.js && rollup -c tools/rollup.browser.min.js",
-		"prepare": "npm test && rm -rf build && npm run build",
+		"prepare": "npm test && rimraf build && npm run build",
 		"test": "karma start && npm run lint",
 		"lint": "eslint src/** tools/** && tslint -c tslint.json types/**.ts",
 		"dev": "npm-run-all --parallel watch serve",
@@ -52,6 +52,7 @@
 		"mocha": "^5.2.0",
 		"npm-run-all": "^4.1.2",
 		"puppeteer": "^1.5.0",
+		"rimraf": "^2.6.2",
 		"rollup": "^0.62.0",
 		"rollup-plugin-babel": "^3.0.4",
 		"rollup-plugin-license": "^0.7.0",