diff --git a/Meta/gn/secondary/Userland/Libraries/LibWeb/CSS/BUILD.gn b/Meta/gn/secondary/Userland/Libraries/LibWeb/CSS/BUILD.gn
index ce75d79619..7a8f4ce605 100644
--- a/Meta/gn/secondary/Userland/Libraries/LibWeb/CSS/BUILD.gn
+++ b/Meta/gn/secondary/Userland/Libraries/LibWeb/CSS/BUILD.gn
@@ -16,6 +16,7 @@ source_set("CSS") {
     "CSSKeyframeRule.cpp",
     "CSSKeyframesRule.cpp",
     "CSSMediaRule.cpp",
+    "CSSNamespaceRule.cpp",
     "CSSNumericType.cpp",
     "CSSRule.cpp",
     "CSSRuleList.cpp",
diff --git a/Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni b/Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni
index 05bef02c05..8021134455 100644
--- a/Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni
+++ b/Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni
@@ -28,6 +28,7 @@ standard_idl_files = [
   "//Userland/Libraries/LibWeb/CSS/CSSKeyframesRule.idl",
   "//Userland/Libraries/LibWeb/CSS/CSSImportRule.idl",
   "//Userland/Libraries/LibWeb/CSS/CSSMediaRule.idl",
+  "//Userland/Libraries/LibWeb/CSS/CSSNamespaceRule.idl",
   "//Userland/Libraries/LibWeb/CSS/CSSRule.idl",
   "//Userland/Libraries/LibWeb/CSS/CSSRuleList.idl",
   "//Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.idl",