diff --git a/third_party/WebIDL/WebIDL.py b/third_party/WebIDL/WebIDL.py
index 40e118e3781..bad5cbe54ca 100644
or identifier == "Serializable"
or identifier == "Abstract"
or identifier == "Inline"
+ or identifier == "Transferable"
):
# Known extended attributes that do not take values
if not attr.noArguments():