diff --git a/Userland/Libraries/LibWeb/DOM/Document.idl b/Userland/Libraries/LibWeb/DOM/Document.idl
index 322f29e245..c6dc9d4544 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.idl
+++ b/Userland/Libraries/LibWeb/DOM/Document.idl
@@ -106,8 +106,8 @@ interface Document : Node {
     [CEReactions] attribute DOMString title;
 
     boolean queryCommandSupported(DOMString commandId);
-    readonly boolean hidden;
-    readonly DOMString visibilityState;
+    readonly attribute boolean hidden;
+    readonly attribute DOMString visibilityState;
 
     [NewObject] NodeIterator createNodeIterator(Node root, optional unsigned long whatToShow = 0xFFFFFFFF, optional NodeFilter? filter = null);
     [NewObject] TreeWalker createTreeWalker(Node root, optional unsigned long whatToShow = 0xFFFFFFFF, optional NodeFilter? filter = null);
diff --git a/Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.idl b/Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.idl
index 38079d9d49..e0d964d7c7 100644
--- a/Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.idl
+++ b/Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.idl
@@ -20,4 +20,4 @@ dictionary ResizeObserverOptions {
 };
 
 // https://drafts.csswg.org/resize-observer/#resize-observer-callback
-callback ResizeObserverCallback = void (sequence<ResizeObserverEntry> entries, ResizeObserver observer);
+callback ResizeObserverCallback = undefined (sequence<ResizeObserverEntry> entries, ResizeObserver observer);
diff --git a/Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBRequest.idl b/Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBRequest.idl
index b08ed51cfd..d02b60b630 100644
--- a/Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBRequest.idl
+++ b/Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBRequest.idl
@@ -2,7 +2,7 @@
 [Exposed=*]
 interface ReadableStreamBYOBRequest {
     // FIXME: This should be an ArrayBufferView
-    readonly attribute any? view;
+    readonly attribute any view;
 
     // FIXME: undefined respond([EnforceRange] unsigned long long bytesWritten);
     // FIXME: undefined respondWithNewView(ArrayBufferView view);