diff --git a/Libraries/LibWeb/ResizeObserver/ResizeObserver.cpp b/Libraries/LibWeb/ResizeObserver/ResizeObserver.cpp
index 06f87fed1ff..636cd57f83f 100644
--- a/Libraries/LibWeb/ResizeObserver/ResizeObserver.cpp
+++ b/Libraries/LibWeb/ResizeObserver/ResizeObserver.cpp
@@ -116,7 +116,7 @@ void ResizeObserver::invoke_callback(ReadonlySpan<GC::Ref<ResizeObserverEntry>>
         MUST(wrapped_records->create_data_property(property_index, record.ptr()));
     }
 
-    (void)WebIDL::invoke_callback(callback, this, WebIDL::ExceptionBehavior::Report, { { wrapped_records } });
+    (void)WebIDL::invoke_callback(callback, this, WebIDL::ExceptionBehavior::Report, { { wrapped_records, this } });
 }
 
 void ResizeObserver::unregister_observer_if_needed()
diff --git a/Tests/LibWeb/Text/input/ResizeObserver/observe.html b/Tests/LibWeb/Text/input/ResizeObserver/observe.html
index 3f4128ddec6..05fec577f0b 100644
--- a/Tests/LibWeb/Text/input/ResizeObserver/observe.html
+++ b/Tests/LibWeb/Text/input/ResizeObserver/observe.html
@@ -23,10 +23,13 @@
             });
         }
 
-        const resizeObserver = new ResizeObserver(function (entries) {
+        const resizeObserver = new ResizeObserver(function (entries, ro) {
             if (this !== resizeObserver) {
                 println("this is not the ResizeObserver instance inside callback");
             }
+            if (ro !== resizeObserver) {
+                println("observer argument is not the ResizeObserver instance inside callback");
+            }
 
             for (let entry of entries) {
                 const { width, height } = entry.contentRect;