diff --git a/lib/fs.js b/lib/fs.js
index 3f2a3cc1ac4761..9d6d5298d77a81 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -56,7 +56,7 @@ function getOptions(options, defaultOptions) {
 
   if (options.encoding !== 'buffer')
     assertEncoding(options.encoding);
-  return options;
+  return Object.assign({}, defaultOptions, options);
 }
 
 function copyObject(source) {
@@ -293,7 +293,7 @@ fs.readFile = function(path, options, callback) {
   }
 
   binding.open(pathModule._makeLong(path),
-               stringToFlags(options.flag || 'r'),
+               stringToFlags(options.flag),
                0o666,
                req);
 };
@@ -1201,7 +1201,7 @@ function writeAll(fd, isUserFd, buffer, offset, length, position, callback_) {
 fs.writeFile = function(path, data, options, callback) {
   callback = maybeCallback(arguments[arguments.length - 1]);
   options = getOptions(options, { encoding: 'utf8', mode: 0o666, flag: 'w' });
-  const flag = options.flag || 'w';
+  const flag = options.flag;
 
   if (isFd(path)) {
     writeFd(path, true);
@@ -1260,7 +1260,7 @@ fs.appendFile = function(path, data, options, callback) {
   options = copyObject(options);
 
   // force append behavior when using a supplied file descriptor
-  if (!options.flag || isFd(path))
+  if (isFd(path))
     options.flag = 'a';
 
   fs.writeFile(path, data, options, callback);
@@ -1739,7 +1739,7 @@ function ReadStream(path, options) {
     return new ReadStream(path, options);
 
   // a little bit bigger buffer and water marks by default
-  options = copyObject(getOptions(options, {}));
+  options = copyObject(getOptions(options, { flag: 'r' }));
   if (options.highWaterMark === undefined)
     options.highWaterMark = 64 * 1024;
 
@@ -1903,7 +1903,7 @@ function WriteStream(path, options) {
   if (!(this instanceof WriteStream))
     return new WriteStream(path, options);
 
-  options = copyObject(getOptions(options, {}));
+  options = copyObject(getOptions(options, {flag: 'w'}));
 
   Writable.call(this, options);
 
diff --git a/test/parallel/test-fs-read-stream-inherit.js b/test/parallel/test-fs-read-stream-inherit.js
index d71dc3d4381272..3ae778ab02b396 100644
--- a/test/parallel/test-fs-read-stream-inherit.js
+++ b/test/parallel/test-fs-read-stream-inherit.js
@@ -48,7 +48,7 @@ let paused = false;
 }
 
 {
-  const file3 = fs.createReadStream(fn, Object.create({encoding: 'utf8'}));
+  const file3 = fs.createReadStream(fn, Object.assign({}, {encoding: 'utf8'}));
   file3.length = 0;
   file3.on('data', function(data) {
     assert.strictEqual(typeof data, 'string');
@@ -66,7 +66,7 @@ let paused = false;
 }
 
 {
-  const options = Object.create({bufferSize: 1, start: 1, end: 2});
+  const options = Object.assign({}, {bufferSize: 1, start: 1, end: 2});
   const file4 = fs.createReadStream(rangeFile, options);
   assert.strictEqual(file4.start, 1);
   assert.strictEqual(file4.end, 2);
@@ -80,7 +80,7 @@ let paused = false;
 }
 
 {
-  const options = Object.create({bufferSize: 1, start: 1});
+  const options = Object.assign({}, {bufferSize: 1, start: 1});
   const file5 = fs.createReadStream(rangeFile, options);
   assert.strictEqual(file5.start, 1);
   file5.data = '';
@@ -94,7 +94,7 @@ let paused = false;
 
 // https://github.com/joyent/node/issues/2320
 {
-  const options = Object.create({bufferSize: 1.23, start: 1});
+  const options = Object.assign({}, {bufferSize: 1.23, start: 1});
   const file6 = fs.createReadStream(rangeFile, options);
   assert.strictEqual(file6.start, 1);
   file6.data = '';
@@ -108,12 +108,12 @@ let paused = false;
 
 {
   assert.throws(function() {
-    fs.createReadStream(rangeFile, Object.create({start: 10, end: 2}));
+    fs.createReadStream(rangeFile, Object.assign({}, {start: 10, end: 2}));
   }, /"start" option must be <= "end" option/);
 }
 
 {
-  const options = Object.create({start: 0, end: 0});
+  const options = Object.assign({}, {start: 0, end: 0});
   const stream = fs.createReadStream(rangeFile, options);
   assert.strictEqual(stream.start, 0);
   assert.strictEqual(stream.end, 0);
@@ -137,7 +137,7 @@ let paused = false;
 
 {
   let file7 =
-    fs.createReadStream(rangeFile, Object.create({autoClose: false }));
+    fs.createReadStream(rangeFile, Object.assign({}, {autoClose: false }));
   assert.strictEqual(file7.autoClose, false);
   file7.on('data', function() {});
   file7.on('end', common.mustCall(function() {
@@ -150,7 +150,7 @@ let paused = false;
 
   function file7Next() {
     // This will tell us if the fd is usable again or not.
-    file7 = fs.createReadStream(null, Object.create({fd: file7.fd, start: 0 }));
+    file7 = fs.createReadStream(null, Object.assign({}, {fd: file7.fd, start: 0 }));
     file7.data = '';
     file7.on('data', function(data) {
       file7.data += data;
@@ -167,7 +167,7 @@ let paused = false;
 
 // Just to make sure autoClose won't close the stream because of error.
 {
-  const options = Object.create({fd: 13337, autoClose: false});
+  const options = Object.assign({}, {fd: 13337, autoClose: false});
   const file8 = fs.createReadStream(null, options);
   file8.on('data', function() {});
   file8.on('error', common.mustCall(function() {}));