diff --git a/doc/api/assert.md b/doc/api/assert.md
index 925108b8fcf..58c3e7c07f0 100644
--- a/doc/api/assert.md
+++ b/doc/api/assert.md
@@ -256,6 +256,7 @@ If the values are not equal, an `AssertionError` is thrown with a `message`
 property set equal to the value of the `message` parameter. If the `message`
 parameter is undefined, a default error message is assigned.
 
+## assert.fail(message)
 ## assert.fail(actual, expected, message, operator)
 <!-- YAML
 added: v0.1.21
@@ -263,7 +264,7 @@ added: v0.1.21
 * `actual` {any}
 * `expected` {any}
 * `message` {any}
-* `operator` {string}
+* `operator` {string} (default: '!=')
 
 Throws an `AssertionError`. If `message` is falsy, the error message is set as
 the values of `actual` and `expected` separated by the provided `operator`.
@@ -277,6 +278,12 @@ assert.fail(1, 2, undefined, '>');
 
 assert.fail(1, 2, 'whoops', '>');
 // AssertionError: whoops
+
+assert.fail('boom');
+// AssertionError: boom
+
+assert.fail('a', 'b');
+// AssertionError: 'a' != 'b'
 ```
 
 ## assert.ifError(value)
diff --git a/lib/assert.js b/lib/assert.js
index 303a00e8aeb..8e421901a81 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -79,6 +79,10 @@ function getMessage(self) {
 // display purposes.
 
 function fail(actual, expected, message, operator, stackStartFunction) {
+  if (arguments.length === 1)
+    message = actual;
+  if (arguments.length === 2)
+    operator = '!=';
   throw new assert.AssertionError({
     message: message,
     actual: actual,
diff --git a/test/parallel/test-assert-fail.js b/test/parallel/test-assert-fail.js
new file mode 100644
index 00000000000..5a321c6bb3b
--- /dev/null
+++ b/test/parallel/test-assert-fail.js
@@ -0,0 +1,33 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+
+// no args
+assert.throws(
+  () => { assert.fail(); },
+  /^AssertionError: undefined undefined undefined$/
+);
+
+// one arg = message
+assert.throws(
+  () => { assert.fail('custom message'); },
+  /^AssertionError: custom message$/
+);
+
+// two args only, operator defaults to '!='
+assert.throws(
+  () => { assert.fail('first', 'second'); },
+  /^AssertionError: 'first' != 'second'$/
+);
+
+// three args
+assert.throws(
+  () => { assert.fail('ignored', 'ignored', 'another custom message'); },
+  /^AssertionError: another custom message$/
+);
+
+// no third arg (but a fourth arg)
+assert.throws(
+  () => { assert.fail('first', 'second', undefined, 'operator'); },
+  /^AssertionError: 'first' operator 'second'$/
+);