diff --git a/lib/fs.js b/lib/fs.js
index 558e9ffa19f7ee..e3bfdabe885734 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -38,6 +38,7 @@ const O_WRONLY = constants.O_WRONLY || 0;
 
 const isWindows = process.platform === 'win32';
 
+const DEBUG = process.env.NODE_DEBUG && /fs/.test(process.env.NODE_DEBUG);
 const errnoException = util._errnoException;
 
 var printDeprecation;
@@ -81,10 +82,39 @@ function throwOptionsError(options) {
     'but got ' + typeof options + ' instead');
 }
 
+function rethrow() {
+  // Only enable in debug mode. A backtrace uses ~1000 bytes of heap space and
+  // is fairly slow to generate.
+  if (DEBUG) {
+    var backtrace = new Error();
+    return function(err) {
+      if (err) {
+        backtrace.stack = err.name + ': ' + err.message +
+                          backtrace.stack.substr(backtrace.name.length);
+        throw backtrace;
+      }
+    };
+  }
+
+  return function(err) {
+    if (err) {
+      throw err;  // Forgot a callback but don't know where? Use NODE_DEBUG=fs
+    }
+  };
+}
+
+function maybeCallback(cb) {
+  return typeof cb === 'function' ? cb : rethrow();
+}
+
 // Ensure that callbacks run in the global context. Only use this function
 // for callbacks that are passed to the binding layer, callbacks that are
 // invoked from JS already run in the proper scope.
 function makeCallback(cb) {
+  if (cb === undefined) {
+    return rethrow();
+  }
+
   if (typeof cb !== 'function') {
     throw new TypeError('"callback" argument must be a function');
   }
@@ -191,9 +221,11 @@ fs.Stats.prototype.isSocket = function() {
 });
 
 fs.access = function(path, mode, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   if (typeof mode === 'function') {
+    callback = mode;
     mode = fs.F_OK;
+  } else if (typeof callback !== 'function') {
+    throw new TypeError('"callback" argument must be a function');
   }
 
   if (!nullCheck(path, callback))
@@ -201,7 +233,7 @@ fs.access = function(path, mode, callback) {
 
   mode = mode | 0;
   var req = new FSReqWrap();
-  req.oncomplete = callback;
+  req.oncomplete = makeCallback(callback);
   binding.access(pathModule._makeLong(path), mode, req);
 };
 
@@ -217,13 +249,12 @@ fs.accessSync = function(path, mode) {
 };
 
 fs.exists = function(path, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   if (!nullCheck(path, cb)) return;
   var req = new FSReqWrap();
   req.oncomplete = cb;
   binding.stat(pathModule._makeLong(path), req);
   function cb(err, stats) {
-    callback(err ? false : true);
+    if (callback) callback(err ? false : true);
   }
 };
 
@@ -237,8 +268,8 @@ fs.existsSync = function(path) {
   }
 };
 
-fs.readFile = function(path, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+fs.readFile = function(path, options, callback_) {
+  var callback = maybeCallback(arguments[arguments.length - 1]);
 
   if (!options || typeof options === 'function') {
     options = { encoding: null, flag: 'r' };
@@ -570,7 +601,7 @@ Object.defineProperty(exports, '_stringToFlags', {
 
 fs.close = function(fd, callback) {
   var req = new FSReqWrap();
-  req.oncomplete = makeCallback(arguments[arguments.length - 1]);
+  req.oncomplete = makeCallback(callback);
   binding.close(fd, req);
 };
 
@@ -588,8 +619,8 @@ function modeNum(m, def) {
   return undefined;
 }
 
-fs.open = function(path, flags, mode, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+fs.open = function(path, flags, mode, callback_) {
+  var callback = makeCallback(arguments[arguments.length - 1]);
   mode = modeNum(mode, 0o666);
 
   if (!nullCheck(path, callback)) return;
@@ -611,7 +642,6 @@ fs.openSync = function(path, flags, mode) {
 
 var readWarned = false;
 fs.read = function(fd, buffer, offset, length, position, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   if (!(buffer instanceof Buffer)) {
     // legacy string interface (fd, length, position, encoding, callback)
     readWarned = printDeprecation('fs.read\'s legacy String interface ' +
@@ -635,20 +665,20 @@ fs.read = function(fd, buffer, offset, length, position, callback) {
       if (bytesRead > 0) {
         tryToStringWithEnd(buffer, encoding, bytesRead, cb);
       } else {
-        cb(err, '', bytesRead);
+        (cb)(err, '', bytesRead);
       }
     };
   }
 
   if (length === 0) {
     return process.nextTick(function() {
-      callback(null, 0, buffer);
+      callback && callback(null, 0, buffer);
     });
   }
 
   function wrapper(err, bytesRead) {
     // Retain a reference to buffer so that it can't be GC'ed too soon.
-    callback(err, bytesRead || 0, buffer);
+    callback && callback(err, bytesRead || 0, buffer);
   }
 
   var req = new FSReqWrap();
@@ -712,7 +742,6 @@ fs.readSync = function(fd, buffer, offset, length, position) {
 // OR
 //  fs.write(fd, string[, position[, encoding]], callback);
 fs.write = function(fd, buffer, offset, length, position, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   function wrapper(err, written) {
     // Retain a reference to buffer so that it can't be GC'ed too soon.
     callback(err, written || 0, buffer);
@@ -724,8 +753,10 @@ fs.write = function(fd, buffer, offset, length, position, callback) {
   if (buffer instanceof Buffer) {
     // if no position is passed then assume null
     if (typeof position === 'function') {
+      callback = position;
       position = null;
     }
+    callback = maybeCallback(callback);
     return binding.writeBuffer(fd, buffer, offset, length, position, req);
   }
 
@@ -740,6 +771,7 @@ fs.write = function(fd, buffer, offset, length, position, callback) {
     }
     length = 'utf8';
   }
+  callback = maybeCallback(position);
   return binding.writeString(fd, buffer, offset, length, req);
 };
 
@@ -761,7 +793,7 @@ fs.writeSync = function(fd, buffer, offset, length, position) {
 };
 
 fs.rename = function(oldPath, newPath, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(oldPath, callback)) return;
   if (!nullCheck(newPath, callback)) return;
   var req = new FSReqWrap();
@@ -782,13 +814,14 @@ fs.truncate = function(path, len, callback) {
   if (typeof path === 'number') {
     return fs.ftruncate(path, len, callback);
   }
-
-  callback = makeCallback(arguments[arguments.length - 1]);
-
-  if (typeof len === 'function' || len === undefined) {
+  if (typeof len === 'function') {
+    callback = len;
+    len = 0;
+  } else if (len === undefined) {
     len = 0;
   }
 
+  callback = maybeCallback(callback);
   fs.open(path, 'r+', function(er, fd) {
     if (er) return callback(er);
     var req = new FSReqWrap();
@@ -822,11 +855,14 @@ fs.truncateSync = function(path, len) {
 };
 
 fs.ftruncate = function(fd, len, callback) {
-  if (typeof len === 'function' || len === undefined) {
+  if (typeof len === 'function') {
+    callback = len;
+    len = 0;
+  } else if (len === undefined) {
     len = 0;
   }
   var req = new FSReqWrap();
-  req.oncomplete = makeCallback(arguments[arguments.length - 1]);
+  req.oncomplete = makeCallback(callback);
   binding.ftruncate(fd, len, req);
 };
 
@@ -838,7 +874,7 @@ fs.ftruncateSync = function(fd, len) {
 };
 
 fs.rmdir = function(path, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = maybeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -862,7 +898,7 @@ fs.fdatasyncSync = function(fd) {
 
 fs.fsync = function(fd, callback) {
   var req = new FSReqWrap();
-  req.oncomplete = makeCallback(arguments[arguments.length - 1]);
+  req.oncomplete = makeCallback(callback);
   binding.fsync(fd, req);
 };
 
@@ -871,7 +907,8 @@ fs.fsyncSync = function(fd) {
 };
 
 fs.mkdir = function(path, mode, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  if (typeof mode === 'function') callback = mode;
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -887,9 +924,9 @@ fs.mkdirSync = function(path, mode) {
 };
 
 fs.readdir = function(path, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   options = options || {};
   if (typeof options === 'function') {
+    callback = options;
     options = {};
   } else if (typeof options === 'string') {
     options = {encoding: options};
@@ -897,6 +934,7 @@ fs.readdir = function(path, options, callback) {
   if (typeof options !== 'object')
     throw new TypeError('"options" must be a string or an object');
 
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -915,12 +953,12 @@ fs.readdirSync = function(path, options) {
 
 fs.fstat = function(fd, callback) {
   var req = new FSReqWrap();
-  req.oncomplete = makeCallback(arguments[arguments.length - 1]);
+  req.oncomplete = makeCallback(callback);
   binding.fstat(fd, req);
 };
 
 fs.lstat = function(path, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -928,7 +966,7 @@ fs.lstat = function(path, callback) {
 };
 
 fs.stat = function(path, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -950,15 +988,16 @@ fs.statSync = function(path) {
 };
 
 fs.readlink = function(path, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   options = options || {};
   if (typeof options === 'function') {
+    callback = options;
     options = {};
   } else if (typeof options === 'string') {
     options = {encoding: options};
   }
   if (typeof options !== 'object')
     throw new TypeError('"options" must be a string or an object');
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -1018,7 +1057,7 @@ fs.symlinkSync = function(target, path, type) {
 };
 
 fs.link = function(srcpath, dstpath, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(srcpath, callback)) return;
   if (!nullCheck(dstpath, callback)) return;
 
@@ -1038,7 +1077,7 @@ fs.linkSync = function(srcpath, dstpath) {
 };
 
 fs.unlink = function(path, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -1052,7 +1091,7 @@ fs.unlinkSync = function(path) {
 
 fs.fchmod = function(fd, mode, callback) {
   var req = new FSReqWrap();
-  req.oncomplete = makeCallback(arguments[arguments.length - 1]);
+  req.oncomplete = makeCallback(callback);
   binding.fchmod(fd, modeNum(mode), req);
 };
 
@@ -1062,7 +1101,7 @@ fs.fchmodSync = function(fd, mode) {
 
 if (constants.hasOwnProperty('O_SYMLINK')) {
   fs.lchmod = function(path, mode, callback) {
-    callback = makeCallback(arguments[arguments.length - 1]);
+    callback = maybeCallback(callback);
     fs.open(path, constants.O_WRONLY | constants.O_SYMLINK, function(err, fd) {
       if (err) {
         callback(err);
@@ -1101,7 +1140,7 @@ if (constants.hasOwnProperty('O_SYMLINK')) {
 
 
 fs.chmod = function(path, mode, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -1117,7 +1156,7 @@ fs.chmodSync = function(path, mode) {
 
 if (constants.hasOwnProperty('O_SYMLINK')) {
   fs.lchown = function(path, uid, gid, callback) {
-    callback = makeCallback(arguments[arguments.length - 1]);
+    callback = maybeCallback(callback);
     fs.open(path, constants.O_WRONLY | constants.O_SYMLINK, function(err, fd) {
       if (err) {
         callback(err);
@@ -1135,7 +1174,7 @@ if (constants.hasOwnProperty('O_SYMLINK')) {
 
 fs.fchown = function(fd, uid, gid, callback) {
   var req = new FSReqWrap();
-  req.oncomplete = makeCallback(arguments[arguments.length - 1]);
+  req.oncomplete = makeCallback(callback);
   binding.fchown(fd, uid, gid, req);
 };
 
@@ -1144,7 +1183,7 @@ fs.fchownSync = function(fd, uid, gid) {
 };
 
 fs.chown = function(path, uid, gid, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -1178,7 +1217,7 @@ function toUnixTimestamp(time) {
 fs._toUnixTimestamp = toUnixTimestamp;
 
 fs.utimes = function(path, atime, mtime, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback)) return;
   var req = new FSReqWrap();
   req.oncomplete = callback;
@@ -1196,11 +1235,10 @@ fs.utimesSync = function(path, atime, mtime) {
 };
 
 fs.futimes = function(fd, atime, mtime, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   atime = toUnixTimestamp(atime);
   mtime = toUnixTimestamp(mtime);
   var req = new FSReqWrap();
-  req.oncomplete = callback;
+  req.oncomplete = makeCallback(callback);
   binding.futimes(fd, atime, mtime, req);
 };
 
@@ -1210,8 +1248,8 @@ fs.futimesSync = function(fd, atime, mtime) {
   binding.futimes(fd, atime, mtime);
 };
 
-function writeAll(fd, isUserFd, buffer, offset, length, position, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+function writeAll(fd, isUserFd, buffer, offset, length, position, callback_) {
+  var callback = maybeCallback(arguments[arguments.length - 1]);
 
   // write(fd, buffer, offset, length, position, callback)
   fs.write(fd, buffer, offset, length, position, function(writeErr, written) {
@@ -1242,8 +1280,8 @@ function writeAll(fd, isUserFd, buffer, offset, length, position, callback) {
   });
 }
 
-fs.writeFile = function(path, data, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+fs.writeFile = function(path, data, options, callback_) {
+  var callback = maybeCallback(arguments[arguments.length - 1]);
 
   if (!options || typeof options === 'function') {
     options = { encoding: 'utf8', mode: 0o666, flag: 'w' };
@@ -1314,8 +1352,8 @@ fs.writeFileSync = function(path, data, options) {
   }
 };
 
-fs.appendFile = function(path, data, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
+fs.appendFile = function(path, data, options, callback_) {
+  var callback = maybeCallback(arguments[arguments.length - 1]);
 
   if (!options || typeof options === 'function') {
     options = { encoding: 'utf8', mode: 0o666, flag: 'a' };
@@ -1470,7 +1508,6 @@ StatWatcher.prototype.stop = function() {
 const statWatchers = new Map();
 
 fs.watchFile = function(filename, options, listener) {
-  listener = makeCallback(arguments[arguments.length - 1]);
   nullCheck(filename);
   filename = pathModule.resolve(filename);
   var stat;
@@ -1486,9 +1523,14 @@ fs.watchFile = function(filename, options, listener) {
   if (options !== null && typeof options === 'object') {
     options = util._extend(defaults, options);
   } else {
+    listener = options;
     options = defaults;
   }
 
+  if (typeof listener !== 'function') {
+    throw new Error('"watchFile()" requires a listener function');
+  }
+
   stat = statWatchers.get(filename);
 
   if (stat === undefined) {
@@ -1534,16 +1576,17 @@ fs.realpathSync = function realpathSync(path, options) {
 
 
 fs.realpath = function realpath(path, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   if (!options) {
     options = {};
   } else if (typeof options === 'function') {
+    callback = options;
     options = {};
   } else if (typeof options === 'string') {
     options = {encoding: options};
   } else if (typeof options !== 'object') {
     throw new TypeError('"options" must be a string or an object');
   }
+  callback = makeCallback(callback);
   if (!nullCheck(path, callback))
     return;
   var req = new FSReqWrap();
@@ -1554,12 +1597,12 @@ fs.realpath = function realpath(path, options, callback) {
 
 
 fs.mkdtemp = function(prefix, options, callback) {
-  callback = makeCallback(arguments[arguments.length - 1]);
   if (!prefix || typeof prefix !== 'string')
     throw new TypeError('filename prefix is required');
 
   options = options || {};
   if (typeof options === 'function') {
+    callback = options;
     options = {};
   } else if (typeof options === 'string') {
     options = {encoding: options};
@@ -1567,6 +1610,7 @@ fs.mkdtemp = function(prefix, options, callback) {
   if (typeof options !== 'object')
     throw new TypeError('"options" must be a string or an object');
 
+  callback = makeCallback(callback);
   if (!nullCheck(prefix, callback)) {
     return;
   }
diff --git a/test/fixtures/test-fs-readfile-error.js b/test/fixtures/test-fs-readfile-error.js
new file mode 100644
index 00000000000000..0638d01ac7655a
--- /dev/null
+++ b/test/fixtures/test-fs-readfile-error.js
@@ -0,0 +1 @@
+require('fs').readFile('/');  // throws EISDIR
diff --git a/test/parallel/test-fs-chmod.js b/test/parallel/test-fs-chmod.js
index 1564734ec64441..954916cbdbb365 100644
--- a/test/parallel/test-fs-chmod.js
+++ b/test/parallel/test-fs-chmod.js
@@ -101,7 +101,7 @@ fs.open(file2, 'a', function(err, fd) {
         assert.equal(mode_sync, fs.fstatSync(fd).mode & 0o777);
       }
       success_count++;
-      fs.closeSync(fd);
+      fs.close(fd);
     }
   });
 });
diff --git a/test/parallel/test-fs-link.js b/test/parallel/test-fs-link.js
index 89d4c25d5bb78e..2cba47bfec83df 100644
--- a/test/parallel/test-fs-link.js
+++ b/test/parallel/test-fs-link.js
@@ -23,14 +23,14 @@ fs.link(srcPath, dstPath, common.mustCall(callback));
 
 assert.throws(
   function() {
-    fs.link(undefined, undefined, () => {});
+    fs.link();
   },
   /src must be a string or Buffer/
 );
 
 assert.throws(
   function() {
-    fs.link('abc', undefined, () => {});
+    fs.link('abc');
   },
   /dest must be a string or Buffer/
 );
diff --git a/test/parallel/test-fs-make-callback.js b/test/parallel/test-fs-make-callback.js
index 8ded34e2b088fd..4fbe64437eaff0 100644
--- a/test/parallel/test-fs-make-callback.js
+++ b/test/parallel/test-fs-make-callback.js
@@ -13,6 +13,9 @@ function test(cb) {
 // Verify the case where a callback function is provided
 assert.doesNotThrow(test(function() {}));
 
+// Passing undefined calls rethrow() internally, which is fine
+assert.doesNotThrow(test(undefined));
+
 // Anything else should throw
 assert.throws(test(null));
 assert.throws(test(true));
diff --git a/test/parallel/test-fs-mkdtemp.js b/test/parallel/test-fs-mkdtemp.js
index 60d1196c5a5631..dd4ab75c22c7aa 100644
--- a/test/parallel/test-fs-mkdtemp.js
+++ b/test/parallel/test-fs-mkdtemp.js
@@ -29,3 +29,8 @@ fs.mkdtemp(path.join(common.tmpDir, 'bar.'), common.mustCall(handler));
 // Same test as above, but making sure that passing an options object doesn't
 // affect the way the callback function is handled.
 fs.mkdtemp(path.join(common.tmpDir, 'bar.'), {}, common.mustCall(handler));
+
+// Making sure that not passing a callback doesn't crash, as a default function
+// is passed internally.
+assert.doesNotThrow(() => fs.mkdtemp(path.join(common.tmpDir, 'bar-')));
+assert.doesNotThrow(() => fs.mkdtemp(path.join(common.tmpDir, 'bar-'), {}));
diff --git a/test/parallel/test-fs-no-callback-errors.js b/test/parallel/test-fs-no-callback-errors.js
deleted file mode 100644
index 0b2bc0d2e3fbb9..00000000000000
--- a/test/parallel/test-fs-no-callback-errors.js
+++ /dev/null
@@ -1,17 +0,0 @@
-'use strict';
-
-require('../common');
-const fs = require('fs');
-const assert = require('assert');
-
-Object.getOwnPropertyNames(fs).filter(
-  (d) => !d.endsWith('Stream') &&       // ignore stream creation functions
-         !d.endsWith('Sync') &&         // ignore synchronous functions
-         typeof fs[d] === 'function' && // ignore anything other than functions
-         d.indexOf('_') === -1 &&       // ignore internal use functions
-         !/^[A-Z]/.test(d) &&           // ignore conventional constructors
-         d !== 'watch' &&               // watch's callback is optional
-         d !== 'unwatchFile'            // unwatchFile's callback is optional
-).forEach(
-  (d) => assert.throws(() => fs[d](), /"callback" argument must be a function/)
-);
diff --git a/test/parallel/test-fs-readfile-error.js b/test/parallel/test-fs-readfile-error.js
new file mode 100644
index 00000000000000..86a2be4e1bc020
--- /dev/null
+++ b/test/parallel/test-fs-readfile-error.js
@@ -0,0 +1,34 @@
+'use strict';
+var common = require('../common');
+var assert = require('assert');
+var exec = require('child_process').exec;
+var path = require('path');
+
+// `fs.readFile('/')` does not fail on FreeBSD, because you can open and read
+// the directory there.
+if (process.platform === 'freebsd') {
+  common.skip('platform not supported.');
+  return;
+}
+
+function test(env, cb) {
+  var filename = path.join(common.fixturesDir, 'test-fs-readfile-error.js');
+  var execPath = '"' + process.execPath + '" "' + filename + '"';
+  var options = { env: Object.assign(process.env, env) };
+  exec(execPath, options, function(err, stdout, stderr) {
+    assert(err);
+    assert.equal(stdout, '');
+    assert.notEqual(stderr, '');
+    cb('' + stderr);
+  });
+}
+
+test({ NODE_DEBUG: '' }, common.mustCall(function(data) {
+  assert(/EISDIR/.test(data));
+  assert(!/test-fs-readfile-error/.test(data));
+}));
+
+test({ NODE_DEBUG: 'fs' }, common.mustCall(function(data) {
+  assert(/EISDIR/.test(data));
+  assert(/test-fs-readfile-error/.test(data));
+}));
diff --git a/test/parallel/test-fs-stat.js b/test/parallel/test-fs-stat.js
index 081ace714becaf..ac68a9ae42c389 100644
--- a/test/parallel/test-fs-stat.js
+++ b/test/parallel/test-fs-stat.js
@@ -28,7 +28,7 @@ fs.open('.', 'r', undefined, common.mustCall(function(err, fd) {
   fs.fstat(fd, common.mustCall(function(err, stats) {
     assert.ifError(err);
     assert.ok(stats.mtime instanceof Date);
-    fs.closeSync(fd);
+    fs.close(fd);
     assert(this === global);
   }));
 
@@ -47,7 +47,7 @@ fs.open('.', 'r', undefined, common.mustCall(function(err, fd) {
     console.dir(stats);
     assert.ok(stats.mtime instanceof Date);
   }
-  fs.closeSync(fd);
+  fs.close(fd);
 }));
 
 console.log(`stating:  ${__filename}`);
diff --git a/test/parallel/test-fs-watchfile.js b/test/parallel/test-fs-watchfile.js
index 270bf270d7fa04..d30261859c39b7 100644
--- a/test/parallel/test-fs-watchfile.js
+++ b/test/parallel/test-fs-watchfile.js
@@ -8,11 +8,11 @@ const assert = require('assert');
 // Basic usage tests.
 assert.throws(function() {
   fs.watchFile('./some-file');
-}, /"callback" argument must be a function/);
+}, /"watchFile\(\)" requires a listener function/);
 
 assert.throws(function() {
   fs.watchFile('./another-file', {}, 'bad listener');
-}, /"callback" argument must be a function/);
+}, /"watchFile\(\)" requires a listener function/);
 
 assert.throws(function() {
   fs.watchFile(new Object(), function() {});