diff --git a/spec/numberformat.html b/spec/numberformat.html
index d708326b..e515cd5a 100644
--- a/spec/numberformat.html
+++ b/spec/numberformat.html
@@ -628,7 +628,7 @@
Intl.NumberFormat.prototype.formatToParts ( _value_ )
1. Let _nf_ be *this* value.
1. If Type(_nf_) is not Object, throw a *TypeError* exception.
- 1. If _nf_ does not have an [[initializedNumberFormat]] internal slot, throw a *TypeError* exception.
+ 1. If _nf_ does not have an [[InitializedNumberFormat]] internal slot, throw a *TypeError* exception.
1. Let _x_ be ? ToNumber(_value_).
1. Return ? FormatNumberToParts(_nf_, _x_).