diff --git a/docs/_writing-tests/testharness-api.md b/docs/_writing-tests/testharness-api.md
index 737804741bde0f7..92a9536b69030fd 100644
--- a/docs/_writing-tests/testharness-api.md
+++ b/docs/_writing-tests/testharness-api.md
@@ -700,6 +700,11 @@ Relies on `===`, distinguishes between `-0` and `+0`, and has a specific check f
 asserts that `expected` is an Array, and `actual` is equal to one of the
 members i.e. `expected.indexOf(actual) != -1`
 
+### `assert_object_equals(actual, expected, description)`
+asserts that `actual` is an object and not null and that all enumerable
+properties on `actual` are own properties on `expected` with the same values,
+recursing if the value is an object and not null.
+
 ### `assert_array_equals(actual, expected, description)`
 asserts that `actual` and `expected` have the same
 length and the value of each indexed property in `actual` is the strictly equal
diff --git a/resources/testharness.js b/resources/testharness.js
index d4bf2920616fe3f..54379c665a85ae4 100644
--- a/resources/testharness.js
+++ b/resources/testharness.js
@@ -997,6 +997,9 @@ policies and contribution forms [3].
 
     function assert_object_equals(actual, expected, description)
     {
+         assert(typeof actual === "object" && actual !== null, "assert_object_equals", description,
+                                                               "value is ${actual}, expected object",
+                                                               {actual: actual});
          //This needs to be improved a great deal
          function check_equal(actual, expected, stack)
          {