diff --git a/spec.html b/spec.html
index 264e39164f..44f77a6f6c 100644
--- a/spec.html
+++ b/spec.html
@@ -4411,13 +4411,12 @@
The Property Descriptor Specification Type
IsAccessorDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _Desc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
1. If _Desc_ has a [[Get]] field, return *true*.
1. If _Desc_ has a [[Set]] field, return *true*.
1. Return *false*.
@@ -4427,13 +4426,12 @@
IsDataDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _Desc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
1. If _Desc_ has a [[Value]] field, return *true*.
1. If _Desc_ has a [[Writable]] field, return *true*.
1. Return *false*.
@@ -4443,13 +4441,12 @@
IsGenericDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _Desc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
1. If IsAccessorDescriptor(_Desc_) is *true*, return *false*.
1. If IsDataDescriptor(_Desc_) is *true*, return *false*.
1. Return *true*.
@@ -14079,6 +14076,7 @@
1. Return ? ArraySetLength(_A_, _Desc_).
1. Else if _P_ is an array index, then
1. Let _lengthDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
+ 1. Assert: _lengthDesc_ is not *undefined*.
1. Assert: IsDataDescriptor(_lengthDesc_) is *true*.
1. Assert: _lengthDesc_.[[Configurable]] is *false*.
1. Let _length_ be _lengthDesc_.[[Value]].
@@ -14168,6 +14166,7 @@
1. If SameValueZero(_newLen_, _numberLen_) is *false*, throw a *RangeError* exception.
1. Set _newLenDesc_.[[Value]] to _newLen_.
1. Let _oldLenDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
+ 1. Assert: _oldLenDesc_ is not *undefined*.
1. Assert: IsDataDescriptor(_oldLenDesc_) is *true*.
1. Assert: _oldLenDesc_.[[Configurable]] is *false*.
1. Let _oldLen_ be _oldLenDesc_.[[Value]].