diff --git a/index.js b/index.js
index 8a030f0..561dbdd 100644
--- a/index.js
+++ b/index.js
@@ -22,7 +22,10 @@ class Configstore {
 		this.path = options.configPath || path.join(configDirectory, pathPrefix);
 
 		if (defaults) {
-			this.all = Object.assign({}, defaults, this.all);
+			this.all = {
+				...defaults,
+				...this.all
+			};
 		}
 	}
 
@@ -55,7 +58,7 @@ class Configstore {
 			// Make sure the folder exists as it could have been deleted in the meantime
 			makeDir.sync(path.dirname(this.path), makeDirOptions);
 
-			writeFileAtomic.sync(this.path, JSON.stringify(value, null, '\t'), writeFileOptions);
+			writeFileAtomic.sync(this.path, JSON.stringify(value, undefined, '\t'), writeFileOptions);
 		} catch (error) {
 			// Improve the message of permission errors
 			if (error.code === 'EACCES') {
diff --git a/package.json b/package.json
index 8dc4154..89dfbd9 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
 		"url": "sindresorhus.com"
 	},
 	"engines": {
-		"node": ">=6"
+		"node": ">=8"
 	},
 	"scripts": {
 		"test": "xo && ava"
@@ -32,15 +32,15 @@
 		"save"
 	],
 	"dependencies": {
-		"dot-prop": "^4.1.0",
+		"dot-prop": "^5.1.0",
 		"graceful-fs": "^4.1.2",
-		"make-dir": "^2.1.0",
-		"unique-string": "^1.0.0",
-		"write-file-atomic": "^2.0.0",
-		"xdg-basedir": "^3.0.0"
+		"make-dir": "^3.0.0",
+		"unique-string": "^2.0.0",
+		"write-file-atomic": "^3.0.0",
+		"xdg-basedir": "^4.0.0"
 	},
 	"devDependencies": {
-		"ava": "^1.3.1",
+		"ava": "^2.1.0",
 		"xo": "^0.24.0"
 	}
 }
diff --git a/readme.md b/readme.md
index e4ebf16..6d8e2d0 100644
--- a/readme.md
+++ b/readme.md
@@ -63,6 +63,8 @@ Default config.
 
 #### options
 
+Type: `object`
+
 ##### globalConfigPath
 
 Type: `boolean`<br>