diff --git a/index.bs b/index.bs
index f7dbd57..003abe6 100644
--- a/index.bs
+++ b/index.bs
@@ -45,7 +45,7 @@ Parsing API {#parsing-api}
 typedef (DOMString or ReadableStream) CSSStringSource;
 typedef (DOMString or CSSStyleValue or CSSParserValue) CSSToken;
 
-partial interface CSS {
+partial namespace CSS {
 	Promise<sequence<CSSParserRule>> parseStylesheet(CSSStringSource css, optional CSSParserOptions options);
 	Promise<sequence<CSSParserRule>> parseRuleList(CSSStringSource css, optional CSSParserOptions options);
 	Promise<CSSParserRule> parseRule(CSSStringSource css, optional CSSParserOptions options);