diff --git a/index.js b/index.js
index e6be6f3..43991c3 100644
--- a/index.js
+++ b/index.js
@@ -6,6 +6,7 @@ const writeFileAtomic = require('write-file-atomic');
 const sortKeys = require('sort-keys');
 const makeDir = require('make-dir');
 const detectIndent = require('detect-indent');
+const isPlainObj = require('is-plain-obj');
 
 const readFile = promisify(fs.readFile);
 
@@ -24,7 +25,7 @@ const init = (fn, filePath, data, options) => {
 		...options
 	};
 
-	if (options.sortKeys) {
+	if (options.sortKeys && isPlainObj(data)) {
 		data = sortKeys(data, {
 			deep: true,
 			compare: typeof options.sortKeys === 'function' ? options.sortKeys : undefined
diff --git a/package.json b/package.json
index 3c8dd44..8756e07 100644
--- a/package.json
+++ b/package.json
@@ -36,6 +36,7 @@
 	"dependencies": {
 		"detect-indent": "^6.0.0",
 		"graceful-fs": "^4.1.15",
+		"is-plain-obj": "^2.0.0",
 		"make-dir": "^3.0.0",
 		"sort-keys": "^3.0.0",
 		"write-file-atomic": "^3.0.0"
diff --git a/test.js b/test.js
index 37458be..7da9624 100644
--- a/test.js
+++ b/test.js
@@ -39,6 +39,9 @@ test('async - {sortKeys: true}', async t => {
 	const tempFile = tempy.file();
 	await writeJsonFile(tempFile, {c: true, b: true, a: true}, {sortKeys: true});
 	t.is(fs.readFileSync(tempFile, 'utf8'), '{\n\t"a": true,\n\t"b": true,\n\t"c": true\n}\n');
+  
+  await writeJsonFile(tempFile, ['c', 'b', 'a'], {sortKeys: true});
+	t.is(fs.readFileSync(tmp, 'utf8'), '[\n\t"c",\n\t"b",\n\t"a"\n]\n');
 });
 
 test('async - {sortKeys: false}', async t => {